I've just bought from TBdress for the first time. The sizes are, of course, pretty petite. I'm an European S, but I ordered L for my dress (I think I might have fit into M too, but it would have been pretty tight) The size chart is pretty accurate though.
So, yes, the sizes are small, but there is a size chart for every dress. (There is no excuse if you buy a size too small :D)
The variety of dresses and clothes in general is huge! Which is a huge +.
The delivery was very fast. It came within two weeks, despite Christmas holiday madness.
Only critique I have: While the dress was beautiful and a good fit and all, quality-wise the clothes are not the best. Of course, the price is very cheap - especially considering those gorgeous designs - but beware that the fabric isn't really good. (but then, what do we except from such a price^^)
Plus, I wish they would have given me a tracking number for my package. They shipping status was never updated - but it arrived, so... it's okay.