GoW isn't out yet, not til March 08.
Right now everyone should be playing Jeanne d'Arc, which is the best SRPG since FFT. And speaking of FFT, Final Fantasy Tactics: The War or the Lions comes out next Tuesday. If it's not the most beautiful thing I've seen in 10 years, beauty doesn't exist.
A brief snapshot of what the new version contains:
-Brand new animated cutscenes, with voice acting
-Two new jobs: Onion Knight and Dark Knight
-Two new characters: Lusa (from FFTA) and Balthier (from FF12)
And there's more. FFT GOTY PSP? Depends on how Silent Hill Origins fares, but it's making a strong case.