he's a very nice looking horse and you should be really happy to have such a nice lease horse. He looks very thoroughbred like, and has decent conformation. His hind legs are a tiny bit camped out behind, but it's minimal. He does have a ewe neck and will benefit from more riding . Honestly, he may be a bit under-muscled in some spots, but he's also really in good condition overall. Don't worry so much about him. He looks to be in good health and generally good conformation. Certainly functional.
Enjoy him and don't waste a minute thinking he is "less than".