I like him! He is a bit post-legged in the hinds, like you said, and has rather upright pasterns in the hinds. He needs more muscle, but that will come with time, and I would like to see a little more weight on him, although having said that I don't think he's thin - I just like to see them a little
chubby, esp. The TBs as they're naturally lean anyway.
But he is a handsome boy, and like HorseLover said, he has really soft eyes. Is he an OTTB?