never got around to playing this one on 3ds, is it worth a fiver?
Yeah, certainly worth $5. Especially the Hyper Drive edition, which has all the additional stages in it. Do note that this is a puzzle-platformer, mostly just a puzzle game which involves some (sometimes tricky) platforming, as opposed to a Mega Man-style game with a block switching gimmick. It's still good, just so you know what you're getting.