I see that he has prospered in your care. He had overgrown feet when you got him and low heels, and was develping an under neck bulging muscle, due to the martingale. You will want to work on developing his upper neck muscles instead of letting him keep his lower neck braced, thus the bulge that develps there.
He is narrow, but his legs are really straight and clean. He looks sturdy and I bet he'd be awesome in endurance riding.