I'm a hard sell on paying full price on a game. Typically only the biggest releases earn an early purchase from me, unless I have loads of old junk to trade in.
That said, I played a friend's copy of Dead Rising for several hours and I will definitely not be buying it until it drops to at least $30.
It's fun enough in that you get to slice through hundreds of zombies in a mall (duh), but some of the missions are boring or a little difficult, and honestly the mission structure could have been a little more free-roaming and GTA-like. It's not that it's a horrible "case file" system, but I personally don't have the time to play through a game a second time to hit everything; and the time constrictions on DR's missions make that a little difficult.
Also, the different weapons are really no more than gimmicks. Once you see the animations, there's no magic. Don't expect any gravity gun contenders, as the only real differences between weapon A and weapon B and weapon C (and so on) are strength and speed.
I'm waiting to see reviews of Madden and/or Saint's Row before making my next game purchase.