Aesthetically, this is my favorite lingerie set ever, but fit wise I should have gone up a size. I would recommend following their size chart, but sizing up if you're on the edge of a size. Both pieces are constructed beautifully, and clearly required considerable time to construct. This isn't the most bust friendly of brands, but they do offer custom sizing on some of their pieces (any of the ones with an adjustable band rather than a solid one). You can also choose different fabrics than standard for any of their pieces, which I did here (the standard would be jersey).
This is the perfect triangle bralette, hands down. I have it in the opaque black bamboo jersey fabric version but it also comes in black mesh, other colours, and deadstock lace fabrics. The fabric is soft and the elastic doesn't dig. All the straps are adjustable. The cups are sewn with a dart such that there's actually enough space for my boobs in there, preventing the cups from wrinkling at the bottom like most bralette cups do.
I love the way the crossover straps look from the back. This thing looks fantastic under tops with low backs or low armholes, or low necklines, or anything really. It's comfortable enough to sleep in, making it perfect for bumming around all day. It's not as supportive as a regular bra though, so don't wear it if you're going to be on your feet all day.