Yea, I think Mariotta will turn out to be a great QB down the road. The Bears won't win when Cutler is on the team, too many holes, but Mariota can be groomed behind him ala Rodgers (another second rated QB) or he can start this year if Cutler is involved in a deal.
The OL has question marks at Center and RT. Neither of which is worth a 1st round pick. Defensively, they have soo many damn players they are trying to find the position for in the front 7, they may be fine there. They may not, just no way to tell really. There's not a Safety I want to see drafted at 7, and their is no reason to bring in a WR until you have your QB.
If the Mariotta falls to the skins, I'm not as certain that the Titans will get a good enough trade for the #2 over all pick, and I see the Bears have traded the Skins, I will be jumping for joy. If I see it at 2, despite what they give up, I'll be excited still because I think the Bears will have the best QB prospect in my time as a fan.