I am 5'9" and 158 lbs and the mediums (or one size fits all) fit great.  They are buttery soft.  The center seam that goes between legs up to waste is reinforced.  It's a nice seam.  One has to be careful not to pull the leggings up too much if not wearing a longish tunic.  But, I think they are terrific!  I received a lot of teacher compliments.