I love love LOVE this look -- exactly the sort of open cup style I have been looking for! So I pounced on it, even though I am more of a 38 band than a 36 band. Turns out, this piece has a VERY firm band -- so if you're a big 34 or a solid 36, might work for you. Me, not as much.
I think less-firm breasts might also have a harder time feeling secure in this style, although it can be a sexy look on anyone. My average to firm B cup feels just fine in it.
Overall, do recommend if you've been looking for something like this! Just be aware of what problems you might run into.