I live in Chicago so I've been around Chicago media and fans. The negatives about his attitude are well documented. But there are a couple of additional criticisms that come up frequently. Just when the Bears would get any kind of drive started, he'd have a tendency to hold the football and just kill you with a sack. The other is hero ball, where he'd throw into double coverage, maybe even off his back foot.
Now, if you want to argue these points, in some years, he had a horrific offensive line. The Bears were trying to rebuild that line for awhile. Second, in the Gase year, his picks were down and his efficiency was up. Also, Gase vouches for him and we all love Gase. He could be maturing. Apparently, after he was diagnosed with diabetes, he's cleaned up his diet etc.
I am eager to see how he meshes with strong personalities like Landry and company.
This is going to be interesting, at least.