Having played the original Dead Rising and absolutely loved it (apart from the 7 day survivor achievement that required you to play for 14 hours straight) I had high expectations for the sequel. Playing Case Zero confirmed for me that, "Yep, this is Dead Rising". 
 
The addition of combo weapons certainly makes for an interesting change to the game (no more running round with a Real Mega Buster owning anything that moves) with Blue Castle being inventive with what you can combine. Psychos are back with a vengeance although they feel a lot cheaper this time round. The biggest change for me is the survivor AI; mainly in the fact that they can survive independently. You tell a survivor to run to a location 9 times of of 10 they'll make it without a scratch, the only ones that can't you can usually carry which makes you both unstoppable. 
 

Glad you are enjoying it. I need to get my hands on a copy.