I bought this when I thought I was a 34 DDD. Nope. So the bra doesn't fit but I still wear it occasionally as the design is awesome and retro. The band definitely runs larger than a 34 and the straps are slightly itchy, but the cups appear true to size and it is relatively comfortable.
The fabric is soft and very stretchy, and the design is pretty. I bought this when I thought I was a 34 DDD and I think that it would probably fit perfectly if that were my size. The shape the cups provide is not very uplifted but is more rounded than I was expecting given the appearance of the bra. With the give in the fabric this would probably be a good bra for someone just over a 34 band as well.