God of War 3?
The biggest thing you get in Gow3 is as big as my apartment.
The fact you climb onto a giant doesn't count. It's just a character filling up the screen with a really small Kratos running around. Yes, it's stunning, but it really can't compare.
And in Kz2 and 3 there virtually nothing going on on screen. During the vehicle sections of kz3 you can't even properly drive the vehicle.
UC has some nice vast environments. Even though there's less going on at once.
Just to be clear: I think UC2 and Kz2 look better then Halo 4. Not incredibly better, but still.