I'm really loving this. I'll probably have to order me another one in black.
For reference, I bought a small, white, and I think I'm somewhere in the B/C range but I'm not sure.
Anyway, this thing is super comfortable. I was a bit skeptical that it would actually feel like cotton (bought a "cotton" binder by another manufacturer that felt like swimsuit material), but it does. The fabric is stretchy enough to let you breath, while still binding pretty well. It doesn't get me flat as a board, but it's completely unnoticeable when you were a button-down shirt. It is plenty long enough to tuck in (perhaps too long, but I'm short). I also really like the broad shoulders, because sometimes tank-tops dig in. It was a total pain to put on (had to learn to step into it), but then again, I've been using binders with zippers in the front so...
Anyway, great buy.