I ordered a size small and this tee fits perfectly but is not skin tight.  I am just shy of 5'4", 120 lbs, and a 32C.  Originally, I ordered a different Rashguard and returned it because it was too tight around my middle.  I wanted some protection from the sun when I go swimming with the kids and didn't have help around to apply sunscreen to my back.  I didn't need anything to use for competitive swimming.  While reading another review someone recommended a "rash tee" instead of a rash guard.  So glad I did; I absolutely love this O'Neill rash tee.  I also like that it dries very quickly.  Another customer said something about the fabric being itchy, and I don't feel that way about it.  I think it feels fine.
***Color seems more like a "smokey-black" than a "black-black" color to me, if that makes sense.