I got one of these tank tops last summer and pretty immediately ordered a couple more. I have three of these now, and just ordered a fourth one. They are comfy, look nice and feel reliable. I've been avoiding vest and tank tops for years and years in the summer, because I don't wear strapless bras, matching bra straps with tank top straps is a hassle and regular tank tops so often end up showing more cleavage than I like on a day-to-day basis, or the bra shows up a lot on the side around the armpit, and so on. You know. These are a great solution and a nice, basic wardrobe staple for hot weather.
The fabric is a soft, sturdy jersey, not flimsy but with a lot of stretch. I find the bra part true to fit on me, both cups and band. I usually wear an EU size 80F-G, I have these in 36F and it's a good fit. I'm curvy in the bottom as well as on top, so I appreciate the slim, but somewhat relaxed fit of the top itself, it fits my hips quite well too. Could be more fitted at the waist for my taste, but that's an easy adjustment I can make myself. I imagine that this would work for a large fairly big range of different body shapes below the bra band.