His shoulder is quite steep, and his cannons look slightly offset; It could be more the stance that he is in though, and the way he toes out, giving that illusion.
His topline appears long, but in actuality isn't; right now, it's his weight and lack of muscle giving him the appearance of a longish back; he has a fairly short back, which is a good thing. His croup however is too short and steep, and ties into hind legs that are very upright. The lack of angulation there, can inhibit his ability to drive from the rear.
Over all, however, for a 20 year old horse, he looks pretty good; kudos for getting him this far.