I absolutely love these shorts! The material is fantastic. Thin, but not to thin, and super comfortable with a bit of stretch. I will be using these shorts for hiking and backpacking. The waistband on the inside is soft which will help with the hip-belt rub I get on my backpack sometimes.
They also look super cute on! Okay, as far as sizing, I am 5'3" and 128 lbs with 25" waist and 36" hips and a round booty - I ordered a medium and a small. I was swimming in the mediums. The smalls fit perfect - they are not tight at all. So they provide room to move during hiking or other activities.
I am ordering another pair asap, as they are that good! On a side note, I also wear the Patagonia Trail Chaser shorts. I feel the Arcteryx Kapta fabric may be a little more durable. But I still love the Trail Chasers too!