I love this tank! It's perfectly cropped, and the underbust seam is SO cute. I got it in white and you can 100% see my nips. I think even if I wore pasties, you could be able to see the outline of the pasties through the material. I'd still buy again, maybe in a darker color. But be careful with the white if you care about your nipples showing. I LOVE that I can comfortably wear it without a bra.
I think it runs true to size if you want a body hugging fit. My measurements: 34" waist, 41" bust (idk my bra size), 5'6" 170lb with an athletic build. I'm usually a size L, and I bought a size L. It fits like a medium support sports bra - very form fitting, which is what I wanted. I probably could also wear a XL, but this top doesn't come in that size.