His hind legs look a bit posty, which isn't uncommon in thoroughbreds. He's over at the knee, another common thoroughbred fault (heck, Secretariat was over at the knee lol). I like his pasterns, although his hinds might be a little long.
I like his shoulder angle and his neck ties in well. He looks to be maybe a little pigeon breasted, but that may just be a weight/muscling issue. His neck looks like it'll be nice once it gets some muscle on it.
I like his back. It's a good length (not too short, but not too long) and looks like with muscling it'll be great.
Overall, he looks like a good-looking thoroughbred.