played the demo today and it will probably lead to me buying it.

Glad, i got the steam deal the other week. Only cost me 3.50 €
And I have to say it is a fun, really, really, really, really challenging game. I am in world three and they have a death count and it is about 1500.
The game is chock full with content. Not only several worlds consisting of 20ish levels each and epic boss fights, but also warp zones, negative worlds, extra characters and lots more.
It is a bummer, it will not come out on wii ware now, but i assume even if it did, it would be more costly then the current steam deal. so, get a controller and buy it there or on xbox if you want to play it. cause it is still well worth it.