You know, I read this stuff and I'm torn. On the one hand, I find it hard to have a personal beef with the guy - football's been his life and I can't say I understand what it feels like to walk away from something like that. As for his waffling and gaffes throughout this, it's honestly on par with the rest of his career - he was always saying/doing stupid stuff, we just blew it off because he was "our Brett".
I do see what the "haters" (I'm using this because it's easy, not because I believe it) are saying, though. If you bleed green and gold, this can feel like a betrayal. And once you look at things from an objective viewpoint, the whole thing gets to be a little pathetic.
Here's what I know: He had his best statistical season in 2007 and led the team to the NFCCG. Prior to that season he worked harder to get in shape than he ever had before in his career. Last year he broke down - I don't think even his apologists can say otherwise. Coincidentally, his preparation last year consisted of throwing to some HS kids.
I think you see where I'm going with this. This year (to our knowledge) his prep has consisted of some rehab work on his arm and throwing to HS kids - he engineered it so he wouldn't have to go to training camp. And he's still got the bum shoulder. So from a strictly physical standpoint, the argument can be made that he's more likely to break down again this year than not.
Minnesota's receivers (except for maybe Harvin) are not better than what he had in NY - they're about the same. Obviously, the RB is better, but T. Jones and the other kid in NY weren't slouches. The Jets broke the bank and assembled a very good o-line; the Vikings are going to start the year with untested guys at center and right tackle - it would be foolish to underestimate the impact losing Birk will have, at least early on.
Other than Peterson and the defense (assuming that secondary can keep it together), I don't see much upgrade from the 2008 Jets to the 2009 Vikes. Both HCs are morons.
All together, while I wish Favre the best in Minny (2 games against GB aside, of course), I'm not sure why everyone's so damn positive he's going to get to, much less win, a Super Bowl with them. Looking at everything, he could easily break down this year like he did last year, and conceivably he could get hurt early on while that o-line tries to gel in front of him. If, hypothetically, Kampmann gets loose on him like he did on Quinn, can a 40-year-old Favre get out of the way? I don't know.
So I don't hate him - and I do wish him luck. But I don't see this being a slam dunk by any means, and if it tanks there are several people who will (and should) lose their jobs over it.