You might have noticed that Favre had a pretty good 2007 season. Actually his stats would have been a career season for a lot of quarterbacks. His completion percentage was the highest of his career (66.5%), while throwing for 28 TDs and 4,155 yards. It was comparable to his last great season in 2004 when he completed 64.1% of his passes for 4,088 yards and 30 TDs. The improvement from 2005-2006 was due in large part to the development of WR Greg Jennings and RB Ryan Grant, but his decision making was a lot better this season and he was more patient (most of the time) with the offense then he had been in either 2005 or 2006. It's an amazing accomplishment at age 38.
The only knock on his incredible 2007 season was his consistency. Of the six quarterbacks who made it to the Pro Bowl (not counting injury replacements) Favre is the most inconsistent. Here's a chart of the six quarterbacks' rating by week along with their average rating, high and low rating, and the number of weeks their rating was below 70.
Only one bad game for Brady and Hasselbeck while Peyton Manning had two back-to-back. Amazingly Big Ben had no bad games. Romo is Favre's closest competition, but two of his bad games (three if you include his playoff game) happened after and during week 15 when he injured his right thumb.
Again, this is not a major criticism, but if he has one thing to work on this offseason it is learning to take what the defense is giving you when the offense isn't playing their best.