I looooooooooove his tail. I just want to braid it LOL can't ya tell I like grooming? ;)
Build wise, he is a bit lanky but a lot of hilly trail rides should sort that out and really make those muscles stand out. He's got a noticeable whither, which I like because its easier for the saddle to grip than a smooth shouldered horse (like my Sunny) his legs appear long in the pictures and kind of on the slender side bone wise, I'd keep a close eye on those joints of his if you start riding him in cutting or reining competitions.
Overall though he looks good, just needs some more muscle definition in the shoulders, along his topline and his rump but a lot of time under the saddle will fix that.
Four things greater than all things are:
Women and horses
And power and war. - Rudyard Kipling