I was watching some of Mahomes' vids on draft breakdown (great site btw) and this are my thoughts on him
When he steps up in the pocket, and he does that at a good rate, he's very accurate, he's like Tony Romo with a better arm, but when he hangs in the pocket and the bad habits begin, he's mix of Jay Cutler with a bad Johnny Manziel.
I would not be opposed to the Bills drafting him but they need to be sure that this guy is a leader and a coachable hard worker.
I still, think the best QB prospect of this draft is Mitch Trubisky (apparently the Jets love the guy)