I got the Butterfly Lace Halter Bra Set as a birthday present to wear for my girlfriend, and it made a great impression. I think the combination of black lace and pink bows balances sexy and sweet, and definitely plays up the idea of a "present." It isn't perfect, but the pluses of the set definitely outweigh the minuses for me.

Material:
The Butterfly set is made up of black lacy material, which looks great and feels good for about ten minutes. After that, it starts to scratch (at least for me), so I would not recommend wearing this set for long periods of time. The bows are a very light, satiny fabric which feels nice against the skin. They are also a brighter pink and, if anything, even larger than they appear in the product photo.

Sizing:
I wear size 8 jeans and dress size and a 36B bra size and got the small/medium set, rather than the medium/large. The top fit very well, but I had to use the third (largest) band setting. The panties also fit really well, and were not too small as I had feared.
This set is adjustable enough that the small/ medium size should fit women who wear between a size 4 and 8. It is too large to be flattering on someone smaller. Anyone larger should get the medium/large size

Top:
The top of the set is a halter bra, which has straps that tie behind the neck and also a band that hooks behind the back. I liked that the top was highly adjustable-- you could alter either the length of the straps or the band. I also found that by pulling the material in the front down you could create a shelf-bra effect, which looked really sexy.
Unfortunately, the bra provided no support AT ALL. It works well to emphasize smaller breasts, but I would not recommend it to anyone larger than a B cup.
I also found the bow on the top too large-- unlike the one in the back, it sometimes flopped forward. It also took attention away from my breasts-- and who wants to be upstaged by their lingerie? It didn't ruin the set for me, but I may copy an earlier reviewer and remove the bow.

Bottom:
The style of the bottom is called "Tanga shorts" and is extremely sexy. Here I thought that the combination of the bow and key hole detail worked together and looked great. It also fit amazingly well. The only drawback I could find is the lack of any kind of liner.

Washing and Care:
According to the instructions, this set should be hand washed, but I put it in the washing machine in a garment bag on "delicate" and it survived undamaged. I would not, however, put it in the dryer. Also, I recommend retying the bows as soon as it's dry and not right before you want to wear it again, since they can take a few minutes to get right.

I've used this set a few times now and I really like it. Removing the bow from the top made it simpler and more flattering. It still isn't comfortable to wear for long periods of time-- but then again, it's lingerie.