If you beat the Dead Rising story mode the correct way and get Overtime Mode, and then beat that correctly and get Infinity Mode... it's pretty epic. Infinity Mode is pretty much real time survival where you can starve to death and stuff. You also have to fight other survivors for their supplies and what not. I like building barricades and stuff while fending off massive hoards of zombies. I must say, Infinity Mode in that game is the good stuff. All in all, it's a great game for what it is. Haven't gotten around to DR2, but I've heard good things about that one as well.
EDIT: Best part about it is the melee imo. When you reach level 50, you can basically rampage through the whole mall for hours with just your fists.