I got a small in these and I am 5'6 125 lbs, when I first put it on it was a little tight, especially at the waist, but it has since stretched out nicely. It's comfortable and feels soft. You can't feel the seams on these, either. So overall, great quality for the price. I would recommend sizing down if you are in between sizes.
The 'leggings as pants' trend doesn't seem to be going away, so if you're going to do it, please buy these! They are thick and opaque, and have enough compression to squeeze everything in while still being comfortable. The high-waisted cut prevents the dreaded muffin-top syndrome. (For sizing reference, I have a 30" waist and 42" hips and bought the L.)
These are literally the most comfortable piece of clothing ever. I own a couple of pairs because of how often I want to wear them (laziness = leggings). The one negative is that they do tend to collect lint pretty easily so make sure to have a lint roller on hand, but they're definitely worth that tiny bit of effort.
