It's an amazing game for sure. It's my fourth favorite game this year. My list would be as follows.
1. MGS4
2. LBP
3. GeOW2
4. FALLOUT 3
It's my gf's favorite game period (for now). By the way, we both have played Oblivion, so much so in fact that we bought it for xbox360 and then again for PS3 and we both find this game infinitely better.