I've only played the first of the series, but I'm willing to put myself down as a steadfast hater.
I could discuss the game from a critical angle and rant about the shallow gameplay or dull soundtrack, how the most interesting part of the game is the first half-hour, etc...but absent of everything else, my main complaint is this (spoilertagged for the easily offended):
Kratos is a f---ing douchebag.
I hate him more than any other video game character ever, even eclipsing previous titleholder Shion Uzuki. He's stuck in Gravelly Fury mode, kills everyone he encounters even (or especially?) if it's unnecessary, and the less said about the sex minigame, the better. The game tries to offer an allegedly shocking explanation for his rage (which you can see coming from ten miles away) but it's no excuse for repulsiveness on this level.
I'm OK with a character who's a bit of a prick, so long as they aren't nasty for nastiness' sake. But Jaffe seems addicted to this idea that sociopathy is a perfect substitute for characterization.
Really, I'd recommend DMC 1/3 (haven't played 4) or Ninja Gaiden Black over GoW in an instant. Not only is the gameplay richer and the challenge deeper, but you won't hate yourself for playing them.