I used to buy similar party dresses at BCBG, Guess, Bebe but would pay far more for them. I think this is a better quality and a better fit. I will say that I ordered the XS, Im a 23 waist, 53 and a 30C so Im pretty petite but my friend whos a 25/26 and 56 borrowed this and she fit in it just fine.
My only word of caution is to those who may be a little more gifted in the boob department: I have small boobs, I tried wearing a strapless bra to make them look a little larger but the fabric would gap under the armpit. I assume if you had larger boobs, you might run into this issue too