Some of them are nice, but a lot of the stocks look low quality. I can't stress enough how important quality is. The light seems a bit strong on one or two of them, and I'm not in love with the light textures on the second one. They're good, but there's always room for improvement. :]
Main flaw I see is lack of contrast in them. The colors are kinda bland.Try using more effects to make them look more interesting. I like the 1st, 2nd, 10th, 14th, and last.
I cant see some of them, but of the ones i can see they're pretty good! I especially like the first one^^