I wear a size 34DD, that is my true size in a regular bra, I'm not one of those women who run around wearing something too small with double boob popping out or too large with extra material. I ordered this bra in a 34DD, the fit around my ribs was perfect, fit snugly on the last hook, which is perfect because as we all know these bras stretch over time. The cups however were a little large in the sense that there was room for them to bounce a small amount. Personally I need my girls strapped down when I'm going to run so this was too large for me. I'm returning for a 34D. However I ordered the black and pink and it is a really cute.
Update: I got the 34D which is strange because the DD fit snug around my ribs, but the 34D is looser, I have to put it on the tightest hook. The boobs are tighter, but it doesn't strap them down like I thought it should. While it is more snug, it is cut funky on the sides to let side boob poke out, and a lot! (If you look at the picture you can see it!)
So it is better than the usual sports bras and for the money. But it's not the best one out there.