Syracuse was train wreck of a program before he took over and he has made them respectable. Every time I have seen his teams play, they play very hard. He developed Nassib into, what I think will be, a very good NFL QB. Also, he was Payton's OC in New Orleans. Parcells, Payton, and Loomis all gave him ringing endorsements as well.
He may not turn out to be good NFL HC but I think he was the best candidate out there. He has HC experience and a NFL background. Horton or McCoy may be good candidates, but they also may just be good coordinators. Marrone has shown to be a good HC.