The biggest problem, and it is a significant one, is that the dark color bleeds very heavily.  I bought a teal color and rinsed it out when I took it from the package.  After 5 minutes of soaking in the sink, the water was dark blue.  Glad I did this instead of wearing it right aay and then putting it in the wash.  If you buy a dark color, be resigned to washing it by hand.
If you go ahead and buy one, take others advice and buy one size up.  I did that and it fits even though the color bleeds heavily.
In retrospect, I would have spent more and bought a Spanx brand.