I've invested a good three hours or so in the game now, and I'd say overall its worth the 5$ for a Castlevania and/or puzzle game fan. The RPG aspects are handled pretty well, and the gameplay is easily adapted to within a few matches.
I do have a few customary gripes, though:
-Only Alucard, Death, Maria, and some of the lesser enemies sprites have been redone in higher definition. Much of the time the 'versus' pre-match screens will show a smooth, higher detail character model standing next to a ripped-directly from SotN pixels and all version.
-Though the music changes as you navigate through the areas of the castle, in the matches themselves its always the same score over and over again, and it gets annoying after awhile.
-The touch screen sensitivity seems a little wonky, although it could be my iphone case.
Other than that, its a swell time!