It doesn't matter whether Dead Rising is "well developed" or not. The team is doing what they can. The game is closer to GTA than RE4, in that you have huge areas with lots of assets. Heck, if it was only a 6th gen system, it would look at best like a GTA game. As it is, it looks about 2-3 three times more detailed than the GTA games on the Xbox.
As for Dead Space (trying to get back on topic here), I don't know. If the game is linear, without lots of enemies, like RE4, then the game could likely look as detailed as RE4. I'd have to find high quality screens and videos to be sure.
A flashy-first game is awesome when it comes out. A great-first game is awesome forever.
Plus, just for the hell of it: Kelly Brook at the 2008 BAFTAs








