LIGHTING - Excellent but a bit too bright on the bow and too dark on the finger. Covering the lens with a see-through cloth would have worked well here, as would moving the lighting down just a bit (would correct both problems)
CHALLENGE - It does meet the challenge, although it goes a little towards sex instead of love. That's just being nit-picky though!
SUBJECT/CROPPING - I think this shot would be more impactful if the fingers were untying the ribbon, instead of playing with it, but that is completely a personal opinion. You need to either move the thong up to create white space at the bottom, or crop the white space out of the top.
PRESENTATION - The tones you used are perfect for this photo. You obviously have a great eye for black and white. The lace would have been more prominent on a black background.
Overall, a very good photo and original idea. Well done!
Nice shot, I almost missed the finger the first time I saw it :) I think I would have liked this better if I could see more of the lace and what it's attached to! -annida