Very good work. Despite the sketchy looks, it has very good anatomy and pose quality.
There are a few things i can't simply ignore. First is the way the right leg seems to connect to the body above the hip, problem not present in the left leg. Second is the way she sits in the rock, as if she had no weight at all, or as if her butt were made of something solid enogh to not deform while sitting. Third and last is the rock itself, wich has barely any defined shape.
Overall: The girl looks nice, as well as her pose and clothes. Leg, butt and rock needs some fixing.