His upbringing is sadly neglectful. Stalling a horse in and of itself is not cruel.. but never handling the horse and just stalling it and feeding it is not exactly kind. He has been kept a prisoner. I wonder how good his eyesight is (not focusing on distant objects is something that is part of an animal's development!). I also wonder at the bone hardness and structure...
His feet need help. He has become slipper footed (and no one can pick his feet up I bet). His heels are curling under and are low with a long toe. I wonder at the thickness of his hoof walls when I see that.. but a good trim is in order and a farrier/vet might give you a better prognosis on the feet. If he has contracted frogs and so forth it may be a long road back (at 2 years old you do have time).
He looks pretty good in type and his sire and grandsire are a decent type. He needs time.. he needs training and handling.. he needs feet done.. He is going to be like starting with a feral horse in a lot of respects. A strong round pen to start (that he cannot jump out of!) and patience.. I think he looks worth it. He does have a very straight hind leg (photo number 2) and he does not have an open angle at the point of shoulder (this may change some.. but the level humorus says he won't jump nicely).
Good luck. He will be a project! :)