Well, i'm sure the style lends it self well since it's based on the same engine. I'm sure quake 4 will be signifigantly different than Doom 3. I have a feeling it will be alot more open than doom 3 for one, and the enemies will probably be alot more creative, since they get to play with the "Alien" theme, also the Quake 2 universe is already established, so they'll have alot more possiblity for story, where as doom 3 was a reinvention of a previous game, quake 4 can go wherever it wants, not to mention it's being doen by Raven and not iD