Just got Madden 06 a few days ago. I've had a chance to try out all the game modes and such, and it's pretty good. I love playing with the new(er) rosters. The two-minute drill is fun, though to this day I've still never scored over 7 points. The minicamps are really fun; I love all of them, especially the running one. I've set the highest score for tackling, which is suprising since I'm REALLY bad at that on Gameboy.
I'm currently doing a season with the Rams, so the Season mode is pretty good.
I have 3 main gripes for this game. One, they only have one song. I know it's Gameboy, so you can't put millions of things on it like you can for XBox. But still, one song?! It gets REALLY annoying after awhile. Two, John Madden has like two phrases in the whole game; and he repeats them VERY often. Lastly, I can't figure out how to make my trades stick outside of Season mode. I'd love to do a Two Minute Drill with T.O. on the Cowboys, but I can't make it work.
Other than that, the game is pretty darn good to me! I'll be a frequent player in the future.