An 8.5 is a "hater" review? That's a great score.
CoO is derivative -- it lifts its visuals and gameplay directly from GoW2, with little to no additions. It is God of War lite, in the sense that it's not a full-scale epic GoW game and it doesn't move the series forward the way a true sequel would. But neither of these means it's bad -- in fact it's great! -- and that's exactly what an 8.5 score reflects.
Don't get me wrong. I think Gamespot has almost zero credibility at this point. But when they're right, and they can back up their opinion with solid arguments, I'm ready to defend them.