I bought a large black and it looks very nice. Can be formal or casual which is one reason I liked it. I worry about the zipper giving out at some point but so far its fine. Fabric feels like its decent quality. Not too thin.
I'm about 5'9" and 145 lbs. The dress is above my knees but not too high. The only problem is that it doesn't hug my body quite right. The back is a little loose and the top of the back by my shoulders is a bit loose too. If I had bigger boobs(I'm a 34b) and probably a bigger butt it would look better. I might have been better off with a medium but I didn't want it to be too tight and show off all my flab. Overall really nice dress. I love how it looks. It'll be easy for me to take in the sides a bit to make it fit a little snugger. Definitely recommend.