I played the demo on my PS3 and I'm loving it. It's not as groundbreaking as "God of War", but it's fun. The imagery is dark and very intense and the cutscenes are actually Japanese Horror Anime! It's the horror aspect which makes it stand apart from Kratos' adventures. But the Christianity-elements will probably make the game a little controversial. Combos are dubbed "Faithful" and "Exalted", I kid you not.
As I played the demo, I mixed up combos and powered up "unholy" attacks. You'll also use the Cross to blast away the damned. I don't think this will be "Ninja Gaiden" hard since the enemy AI isn't as aggressive. Still, the game's sound effects are awesome and the musical score is epic (channeling "The Omen"). I can't wait for it!