mādhurīṁ prākaṭayantam ujjvalāṁ
śrīpater api variṣṭha sauṣṭhavām
indirā madhura goṣṭha sundarī
vṛnda vismayakara prabhonnatam

O Kṛṣṇa! The sweet beauty of Your splendid form defeats that of Śrīpati (Lord Viṣṇu) in lustre! O Rādhe! Your elevated splendour astonishes all the beautiful girls of Vraja that are themselves sweeter than even Indirā (the goddess of fortune)!

YUGALA MĀDHURĪḤ  (Dual Sweetness)

Makaranda Kaṇā Vyākhyā by Radhakunda Mahanta Sri Srimat Ananta das Babaji:

In this verse, Śrī Rūpa relishes the Yugala-mādhurī. The more he relishes, the more he thirsts, and the more he thirsts the more he relishes.
In this way it gradually continues.
Everyone in the world, upto the Vaikuṇṭha-planets, all the moving and non-moving beings, all the men and women, even Lakṣmī-Nārāyaṇa, is attracted to the name ‘Kṛṣṇa’. He attracts everyone’s heart and mind with His all-pleasing form and qualities and draws everyone naturally towards Himself.

vṛndāvane aprākṛta navīna madana;
kāma gāyatrī kāma bīje yāra upāsana
puruṣa joṣit kibā sthāvara jaṅgama;
sarva cittākarṣaka sākṣān manmatha madana
(Caitanya Caritāmṛta)

“The transcendental youthful Cupid of Vṛndāvana is worshipable with the Kāma Gāyatrī and the Kāma bīja. Since He is directly Cupid Himself He attracts the minds of everyone – men, women, mobile and immobile creatures.”

Śrī Kṛṣṇa’s form is asamordhva (nothing equals or excels it).
The Bhāgavata says: lāvaṇya sāram asamordhvam ananya siddham –
“Kṛṣṇa’s form is the essence of elegance, it is exclusively perfect, unrivalled, unequalled and unsurpassed.”
His beauty defeats even that of Kamalāpati Śrī Nārāyaṇa. Śrī Caitanya Mahāprabhu, assuming the mood of Śrī Rādhā, took Śrī Sanātana Gosvāmī by the hand, considering him to be His sakhī, and sang:

sakhi he! kon tap koilo gopīgaṇa?
kṛṣṇa rūpa sumādhurī,             
pibi pibi netra bhari
ślāghya kore janma tanu mane.

“O sakhi! What penances have the gopīs performed that they can drink the sweetness of Kṛṣṇa with their eyes, glorifying their births, bodies and minds?”

ye mādhurī ūrdhva āna,     
nāhi yāra samāna,
paravyome svarūpera gaṇe.
yeho sab avatārī,            
paravyome adhikārī,
e mādhurya nāhi nārāyaṇe

“There is nothing higher than or equal to this sweetness. Even all the transcendental forms that dominate over Vaikuṇṭha and descend into this world, such as Śrī Nārāyana, do not have this sweetness!”

tāte sāksī sei ramā,         
nārāyaṇera priyatamā,
pativratā-gaṇera upāsyā.
teho ye mādhurya lobhe,          
chāḍi sab kāma bhoge,
vrata kori korilo tapasyā.

“That is clearly shown by the behaviour of Ramā (Lakṣmī), the beloved of Lord Nārāyaṇa, who is worshipped by all the chaste girls. She gave up all desires and enjoyment, being attracted to Kṛṣṇa’s sweetness and took vows of penance (to propitiate Him).”

This is confirmed in Śrīmad Bhāgavata (10.16.36): yad vāñchayā śrīr lalanācarat tapo vihāya kāmān suciraṁ dhṛta vratā –  “Desiring this (Kṛṣṇa’s lotus-feet), Śrī (Lakṣmī) gave up all desires and performed penances for long.”

There is also a story to this tenor in the Padma Purāna:

Once Lakṣmīdevī, becoming eager for Kṛṣṇa’s sweetness, engaged in severe penance in Vṛndāvana. Being satisfied with her penance, the Lord once revealed Himself to her and asked her why she was engaged in these austerities. Devī then said: “I want to attain You the way the gopīs in Vṛndāvana did.”
Śrī Kṛṣṇa replied: “That is absolutely impossible, because your feelings towards Me are different. They are feelings of awe and reverence, and the gopīs’ love for Me is one of pure sweetness (intimacy). Without such a sweet attitude it is impossible to attain My service in Vraja!”
When Lakṣmī-devī heard these words, she became somewhat morose and said:
“O Lord! Let me then at least reside on Your chest like a golden line!” T
he Lord said: “All right, so be it.”

From that momement on Kamalā-devī resides on Kṛṣṇa’s left chest as a golden stripe (svarṇa rekhā).
According to the Gosvāmīs this Lakṣmī mentioned in the Padma Purāṇa is a different svarūpa (manifestation) from the one mentioned previously in Śrīmād Bhāgavata.
From these quotations, it is easily understood that the sweetness of Śrī Kṛṣṇa is more amazing than the sweetness of Śrīpati.

On the other side it is also seen that the Kṛṣṇa-priyā gopīs could not become attracted to the four-armed form of Lord Nārāyana, even after seeing it with their own eyes. One time Kṛṣṇa showed them His four-armed form just to joke with them, but the gopīs failed to become attracted to it.

svayaṁ bhagavattve Kṛṣṇa hare lakṣmīra mana;
gopikāra mana harite nāre nārāyaṇa
nārāyaṇera kā kathā – śrī Kṛṣṇa āpane;
gopikāre hāsya korite hoy nārāyaṇe
caturbhuja mūrti dekhāya gopīgaṇa āge;
sei kṛṣṇe gopikāra nahe anurāge
(Caitanya Caritāmṛta) 

“Because He is the Original Personality of Godhead Śrī Kṛṣṇa can steal Lakṣmī’s mind, but Nārāyaṇa cannot steal the gopīs’ mind! What to speak of Nārāyaṇa, even Kṛṣṇa Himself could not attract the gopīs by jokingly assuming a four-armed form like Nārāyaṇa’s!”

On the contrary, when the gopīs saw Kṛṣṇa in this four-armed form they simply prayed to Him to show them their beloved Vrajendra-nandana: 

namo nārāyaṇa deva! koroho prasāda;
kṛṣṇa saṅga deho āmāra ghucāo viṣāda

“O Lord Nārāyaṇa! We offer our obeisances unto You! Be kind to us and give us the company of Kṛṣṇa! Please remove our sorrow!”

Through this it is established that the beauty and sweetness of Śrī Nārāyaṇa is inferior to the beauty and sweetness of Śrī Kṛṣṇa.
The sweetness of Śrī Kṛṣṇa, who is the most beautiful boy in the three worlds, enchants all the mobile and immobile creatures of the three worlds.

trailokya saubhagam idaṁ ca nirīkṣya rūpaṁ yad go dvija druma mṛgāḥ pulakānyavibhran (Bhāgavata) –
The Vraja-gopīs said: O dearly beloved! Seeing this sweet form of Yours, which is the most beautiful form in all the three worlds, the cows remain gazing at Your face with unblinking eyes, the birds like the male and female parrots are sitting on the branches of the trees and are meditating on You with closed eyes, and Vraja’s trees, who show goose pimples in the form of their sprouts and who shed tears in the form of their trickling honey, consider themselves blessed when they touch your feet with their branches that are bowing down due to the heavy weight of ripe fruits they bear. When the animals, birds, trees and vines are in such a condition, then what doubt can there be that the human men and women are floating in a stream of sweetness?

The Dhīra Lalita-hero Śrī Kṛṣṇa is supreme and unrivalled in beauty, sweetness, dressing, ornamenting and in expertly displaying His feelings.
In this He excels all other mundane and transcendental heroes, including the innumerable forms of Godhead, headed by the Lord of Paravyoma Śrī Nārāyaṇa.
For this reason almost all the devotee-poets of the world have chosen Vṛndāvana Vihārī as their subject.
After all, where can such sweet cherry-lips, such a delectable smile, such cool, nectarean sounds, such cool glances, such wide reddish eyes and such a heroic flute player be found other than in Vrajendranandana?

There are no words to describe how especially the devotees that take shelter of the madhura rasa view the embodiment of the erotic flavours Śrī Kṛṣṇa in such a wonderful and special way.

The Gosvāmīs are Rādhā’s maidservants in Vraja and in their mahā-bhāva-eyes Madana Mohana is most sweet.
Śrīla Raghunātha dāsa Gosvāmī has written:

vidhi kṛta vidhu sṛṣṭi vyarthatākāri vaktra
dyuti lava hṛta rādhā sthūla mānāndhakāraḥ
smita lapita madhūlyonmāditaitad dhṛṣīkaḥ
sphurati madana pūrvaḥ ko’pi gopāla eṣaḥ
śarad udita saroja vrāta vitrāsi netrāñ-
cala kuṭila kaṭāksair mandaroddaṇḍa cālaiḥ
jhaṭiti mathita rādhā svānta dugdhārṇavāntaḥ
sphurati madana pūrvaḥ ko’pi gopāla eṣaḥ
(Stavāvalī) 

“The honey of His smiles and words maddening Rādhā’s senses and a single ray of the splendour of His face removing the dense darkness of Her proud anger and making useless the moon created by Lord Brahmā, some indescribable Madana Gopāla is splendidly manifest. His crooked sidelong glances frightening the blooming autumn lotus flowers and churning the depths of Rādhā’s heart with the churning-rod of Mount Mandara, some indescribable Śrī Madana Gopāla is splendidly manifest here in Vraja.”

mādhurya and mādhurī means the same thing.

mādhuryaṁ nāma ceṣṭānāṁ sarvāvasthāṣu cārutā
(Bhakti Rasāmṛta Sindhu)

“Activities that are enchanting in all circumstances are called mādhurya.”

This sweetness is a great problem for the eyes of the premavatī Vrajasundarīs:

sakhi! ke o nāgara,           rasera sāgara,       dāḍāiye aśoka mūle.
se rūpa laharī,          lāvaṇya mādhurī,                 heriyā nayāna bhule.
nīla utapala,              dala sukomala,     jiniyā varaṇa śobhā,
dalita kāñcana,       jiniyā vasana,             kulavatī manolobhā
cañcala nayāna,          kāmera sandhāna,         marame hānaye yāra
kulera dharama,         bharama sarama,            sab dūre yāy tāra
śravaṇa kuṇḍala,                kore jhalamala,               saghana kampita cūḍe
tāhāra upori,             bhramarā bhramarī,           madhu lobhe boise uḍe
tribhaṅga hoiyā,     kore veṇu loiyā,     madhura madhura bāya.
locana vacana,      bhuvana mohana,     sei śyāma cāṅda rāy

“Sakhi! Who is this hero, this ocean of rasa, standing there at the base of that Aśoka-tree? My eyes forget everything when they meet with the waves of His form, filled with sweet elegance!
His complexion defeats the luster of tender blue lotus petals and His dress, that defeats the lustre of molten gold, attracts the minds of all the young married girls! His restless eyes are like Cupid’s arrows that pierce the heart and that casts all family duties and all shame far away! The earrings on His ears are shimmering and His crown sways on His head. Above that, male and female bees are flying, thirsty after honey! He stands in His threefold bending form and takes his flute in his hands, playing it ever-so-sweetly.
The words and the eyes of this moonlike Śyāma Rāya are enchanting the world!”

What goes for Śyāma also goes for Svāminī!
Śrī Rūpa said: indirā madhura goṣṭha-sundarī vṛnda vismayakara prabhonnatām – “She astonishes even the beautiful girls of Vraja, that are themselves sweeter than the goddess of fortune Indirā, with the sweetness of Her body!”

The sweetness of the gopīs’ forms, qualities, pastimes and love are even sweeter than Kamalā.
Śrī Rūpa writes in his Ujjvala Nīlamaṇi: āruṇyā api mādhurī parimala vyākṣipta lakṣmī śriyaḥ –  “Although they are just forestgirls their sweetness and fragrance defeats even the opulence of Lakṣmī.”

The festival of Rādhā’s form astonishes even these Vrajasundarīs!

Śrīpāda Prabodhānanda Sarasvatī has written:

subhaga śikhara lakṣmī koṭi kāmyaika pādā
dhṛta nakha maṇi candra jyotir āmoda mātrā
ati madhura caritrānaṅga līlā vilāsā
mama hṛdi rasa-mūrti sphūrtim āyātu rādhā
nava rasa mada ghūrṇan mādhava prāṇa-koṭi
priya nakha maṇi śobhā sarva saubhāgya bhūmiḥ
sphuratu hṛdi sadā me kāpi kāśmīra rocir
vraja nagara kiśorīvṛnda sīmanta bhūṣā
(Saṅgīta Mādhavam,  24 and 25)

“May Rādhā, the embodiment of rasa, whose lotus-feet are coveted by millions of gopīs that are more fortunate and beautiful than the goddess of fortune, who carries pure bliss in the moonbeams that emanate from Her jewel-like nails, whose character is very sweet and whose pastimes are full of erotic bliss, be manifest in my heart!
May some girl, who is the crown jewel of all the adolescent girls of Vraja, who shines with the luster of vermilion, who is the reservoir of all good fortune and whose beautiful toenails are dearer than millions of lives to Mādhava, who is dizzy with the intoxication of fresh rasa, always be manifest in my heart.”

Śrī Rādhā is Vṛndāvana’s sweetness Herself! It is as if a flood of sweet rasa awakens within a nectar-river of prema.
Without executing loving devotional service this sweetness can not be experienced.
It is only manifest spontaneously in the hearts of those who practise this with a pure attitude.
The whole world is blessed by touching a mere drop of this ocean of sweetness, which astonishes the eyes, mind and the heart.
A person who experiences this astonishment won’t be able to express it with words! Hence Śrī Rūpa says:
Śrī Rādhā’s sweetness astonishes the minds of even the Vrajasundarīs!

śrī-pati hoite ati,         ujjvala madhura bhāti,
vrajendranandana parakāśa.
lakṣmī jini manoramā,               śata koṭi vrajāṅganā,
(yāder) rāi rūpe parama ullāsa.

“Vrajendranandana’s appearance shines more brightly and sweetly than Śrīpati and Rāi’s form gives the pinnacle of joy to millions of Vraja-gopīs, that in their turn enchant the goddess of fortune!”