2-D Adventure Platformers rock, I imagine a fully 3-D world be awesome, as Metroid Prime looks to be, but right now I'm more than content with 2-D worlds and 3-D objects and effects.
And I also thought that Konami was going to "redo", for lack of better term, The N64 game for Dreamcast, I'm sure they recived bitter backlash from the fans after Castlevania 64, and they didn't want screw this one up. But I think they couldn't quite do it, so they cancelled it in favor for another 2-D. I say this because, the (knowledgable?) dude at EB said that the next Castlevania that will be released would be another 2-D platformer that would have more CSoN elements than anything else.