My main complaint with this game is the franchise mode. Sure, I play online and against my buddies, but most of my time on the game is spent in the franchise mode. In Madden '06 for the current gen Xbox, the game was nearly perfect in this aspect.
However, in '07 for the 360, the franchise mode is boring, and, as I've heard other people put it, it has no soul. No celebrations for winning games/Superbowl, no fantasy draft, no player editing, and no faces for new players are all things that really get to me.
I will buy Madden '08, but only because Vince Young is on the cover. If I didn't want to collect the case, then I would not even be considering purchasing the game. I fully expect to be disappointed by Madden '08.