These feel great to wear and at ~155lbs (+/- 5lbs depending on the day) and 5' 10", the Medium is a perfect fit for me. I also got a Small because I wasn't sure on the proper size, but that was a bit tight; still wearable, but the Mediums feel better.
The sides open a little more than most of my other thai shorts, but that's the style that I like, so these are great. And the design is even cooler up close than in the pics!