After reading mixed reviews, I ordered my regular bra size of 34D. When I first took it out of the package I just laughed because I did not see any way that this would fit in the cup area. I tried it on and much to my surprise, I does fit, but only just barely. It will work for very low cut tops and the back strap is also really low, which is a big plus. The strap fits around my ribcage well, and I like that the shoulder straps are adjustable but there's definitely a bit more spillage from the cups than I usually prefer. A double D cup would have provided the perfect fit & coverage for my own comfort level, but I'm also used to a good bit more coverage in the cup area so maybe this is just a "getting used to it" issue for me personally.
Unlike some of the reviewers, I didn't feel as though this was UNsupportive, it definitely provided plenty of support for my needs, but I can see where a lot of busty women may feel this fits odd or isn't as supportive as they're used to. I suggest going up a cup size if you're in between cups, or ordering your regular size and then one cup size up and returning the one that didn't fit if you're on the fence because once I adjusted the straps to my liking, this really IS a decent buy, especially at this price point. I was pleasantly surprised. :)