Kolb should be much better than Fitzpatrick, provided Buffalo's OL can help him stay on his feet. He helped the Cardinals get to 4-0 and had 9 TDs to 3 INTs last season before he got hurt.
Eh, I think Kolb is a stopgap / transition QB for the Bills. Obviously keeping Fitzpatrick wasn't an option after the GM brutalized him in the media, and there was no way in hell they were going to trot out Tarvaris Jackson's broken soul. Their defense is mediocre at best, and they really don't have many legitimate weapons on offense. This year's draft sucks out loud for quarterbacks; given how quiet the Bills have been in free agency, everything points to them having a 2 - 4-win season and praying that Johnny Manziel declares for the draft in 2014.
Basically, Kolb is a league-average quarterback who was on the worst possible team for a non-elite quarterback to be, given that in 14 starts with the Cardinals he was sacked 57 times. But, he is not
a great decision-maker, and he sits on the ball entirely too long. He has decent mobility to extend plays, and adequate but not great velocity -- so he can put it where it needs to be in intermediate and short passing situations, but if he has make any kind of throw across his body or against his momentum, it's going to end in tears for everyone except the opposing team's defense.
He isn't a tremendous upgrade over Fitzpatrick (it's really a lateral move; their statistics compare pretty well to each other), but they saved a lot of money by choosing him and cutting Fitzpatrick, and his play is adequate given the money saved.
That being said, there's got to be some injury concern on the Bills' part, because Kolb has yet to reach double-digit starts in any season. He's also going from throwing to Larry Fitzgerald to throwing to Stevie Johnson ... which is a downgrade any way you look at it.