My quarab and I used to run barrels, he loved it too! He was also a bay, lol!
Other than what tinyliny pointed out about his croup, the one thing that really pops out to me are his front pasterns. They look very upright to me. Other than that, I would have to agree- I think he's a very nice looking horse. Good short pasterns, good bone, he looks balanced to me. I love his head and neck, too.