I'm a big fan of it. If people are thinking Brian is a KF clone and/or puppet they are way off IMO. He's actually the one person that can get KF to make changes. Of course there isn't going to be some big overhall of the offense, but the Greg Davis passing game never jived with the running game. The running game has always been a strength and will continue to be one. I think Brian will be able to incorporate a passing game that is more of a complement to the running game.
Just thinking back to the KOK passing offense, the middle of the field was used a ton. Play action to the TE was used over and over and over. Greg didn't know the middle of the field even existed. All the horizontal stuff was completely brought in by Greg. Sure there were bubble screens and things like that before him, but nowhere near the short stuff that has happened over the past few years.
I think Brian will take things back towards the KOK model (e.g., use the center of the field, get the TEs more involved, keep the safties more honest, etc.), but put his own stamp on it. His time with the Patriots is probably being talked up too much, but there's no doubt he had to pick up some things while spending time there with Belichek and O'Brien. And he clearly knows the running game inside and out.
I think I'd honestly be excited for the hire even if his last name wasn't Ferentz.