Apologies for the doulbe post (again).
Anyway, have you tried the Ninja Turtles games on 3DS? I got my boy one and he loves it! It's not as good as the Castlevania titles on DS (in MY opinion - he never got into them), but the one we have, a least, is well worth checking out... its just a pity that I can't think what it's called, though the box does have the Nickleodeon logo on it.
I also heard that Batman: Arkham is like Castlevania so picked up a copy dirt cheap on Amazon (Ł5 cheap!)... but I've not really had the time to play it so can't confirm that.