I never want to take these off! The material is soo soft, some of my yoga pants are kinda stiff seeming because they are thicker material. But these are very light weight and stretchy. Easy on, easy off (if you can convince yourself to actually take them off!) and they are incredibly breathable (how do I even word that right?!) Really, you will not get hot or stuffy in these bad boys.
I will likely be purchasing the matching top as well as other colors.
I purchased the aqua color and love it, it is just like the picture.
I also went with the small, I am about 5' 1" and around 115lbs I went with small cause I have a booty and it fits great. Im sure xs would have fit too but I am very happy with the small!