Very good analysis, doddpower. I missed a big chunk of the second half, but I think I agree with pretty much everything you wrote. One possible exception is Graham Harrell. I didn't think he looked terrible, although I agree that he's not yet ready to be a good backup QB.
My knock on Matt Flynn last year, even after the nice performance against the Patriots, was that he lacked arm strength. I saw no improvement in that area against the Browns. It was all dinking and dunking. He's a good game manager, and I was especially impressed with this two-minute drill at the end of the half, but I think that if teams get a chance to game plan for him in the regular season, they will challenge him to throw the ball downfield, and I see no evidence yet that he'll be able to do it with any kind of effectiveness. That's why I don't think Flynn will be a hot commodity on the open market.
I thought Harrell looked stronger-armed than Flynn, though of course he is far less polished. Possibly, though, Harrell looked worse than he is because he was playing with the third and fourth stringers. The protection was terrible and the route running was chaotic.
To answer Nerdmann's question, Brandon Jackson had a few nice runs, but nothing that made me think he will be a good #1 RB. He benefited from a poor performance by the Packers' second string defense. Watching Lee and Bush run around out there in Cleveland, it seems like a miracle that they played as well as they did in the second half of the Super Bowl.
I loved the big hit and wrap-up by Morgan Burnett, followed by a nice tackle on the perimeter a little while later. I didn't like his run defense last year, but he looked tough against the Browns. That's a very good sign.