I have finally gone swimming in this (cold river water), and I love it. The only complaint I really have with it is that the only color choice that was left by May was the black, which is okay. I am wearing it with a pair of "sits at the waist" black swim shorts. I can't do the current hipster styles but  I think it would work OK with them.
I am fit, I work out and have strong arms and shoulders, but I am small-boned, and I am pear-shaped with large hips. The sleeve ends at my wrists are a bit loose in the water, but everywhere else fits just right, without being too tight when dry or wet (I was worried about the neck, as I hate tight things at my neck, but it is perfect). The length is great, and I love the side cut at the hips, it doesn't ride up at all like other rashguards (my waist has a bulge just below the belly-button from surgery there. No problem for this top!). The side cut / fit and the shelf bra make the Girls4Sport rashguard unique as far as I know.
It dries as well as a regular swim suit would - it drains fast and doesn't hold much water but I can't dry it completely with a towel. My arms felt a bit chilly in the wind. It might run small but I had first ordered a small based on my bra size, which may not be how to size it (maybe I should have measured the widest part of the bust instead?). The medium is perfect.

Ordered what I thought would be my size, a small, my bra size is 34, but the small was way tight around the shoulders, chest and upper arms. The length was pretty good, and the shaping and cut, especially around the hips, does look and feel as if it will stay in place as promised. But I'm exchanging it for a medium, which hasn't arrived yet, so I haven't water tested it yet.

This does fit very very snugly, so I ordered a size up and am very happy with it.  It makes outdoor winter swimming (in Los Angeles) very comfortable.