I dunno. As far as Metroid-style, RPG-infused, side-scrolling games go, it's basically perfect. It doesn't have a whole lot in common with the Castlevania games that came before it (apart from the title and the Big Bad), but it's still a really great game. It's just not a "pure" Castlevania experience.
I am pretty tired of the "Metroidvania" formula now though. I haven't played it yet, but Castlevania ReBirth looks to be the best thing Konami has done with the franchise since... well, since Symphony of the Night.