I've finished GoW trilogy recently (and PSP version long time ago) and must say - first one was monotonous at times. Second one was very good, with much more variety and even better design. But the third GoW is the real masterpiece amongst action games (like Uncharted 2 for me, but that's other kind of action

). And it finally has a plot! First three titles (with PSP one) look like modest prologue to GoW 3.
And I don't want to compare it with Lords of Shadow (not yet). I just want to say, that if new Castlevania will be even a little bit worst than GoW 3, it still will be one hell of a game!
Since Shadow of the Colossus gigantic enemies are quite popular, but it's still not that easy to make such battle unforgettable experience. I hope MercurySteam will do it right.