I think, just like Newton, people are seriously blowing the week 1 performance out of hand.
Yes, Collins struggled, that was obvious. The Colts were down early and forced him to throw a lot. Outside of the fumbles Collins wasn't too bad. I forgive Collins for the fumbles under center because that's merely a timing thing that needs to be worked out. If you take that away and look at it he didn't have a horrendous game. In fact he had a 82 qb rating or something like that, that's about average.
The problem is just he's new to the offense, has to get used to the playbook/center, etc, and was down early forcing the Colts to lean on him, and he's certainly no Manning when it comes to that situation in Indianapolis.