I love these leggings. I wasn't sure what size to get, went with a medium, and they fit pretty well. I am 5'5", 120lbs. My legs are probably a little on the shorter side, so the leggings are a tad long, but it's fine. They are so extremely comfortable, don't stretch out in the knees, and the fabric is of great quality. Perfect to wear working out or daily on the go. If I ordered again, I'd probably go with a small, just for the length, but the mediums fit well enough that I don't want to go through the hassle of returning them.
Recently bought these after searching for a perfect pair of leggings, and these are indeed perfect. Everything I want in a legging: comfortable, good for running, yoga, and gym climbing (haven't taken them to the outdoors yet), very basic looking, doubles as base layer and pants (for days I don't feel like putting on real pants which is more often than not). Totally worth the price!
I have a few pair of prAna pants, some in my usual size (L - 5'11" 160#) and some in XL. I ordered these in XL and ought to have bought a L. They are long enough (YAY) and fit well through the knee, then get gradually looser up to the waistband, which is an inch or two too big. They are fine for wearing around town but I'm afraid they wouldn't make it through a run. That said, they are very flattering and comfortable and made from a substantial knit - perfect for winter, fall, and cool spring temps. I will order a 2nd pair in my size once the price is right.