I've read quite a few hands-on impressions of Nintendo's Super Paper Mario (coming to the Wii in early April) from GDC 2007 today, and without fail they are "thumbs up" positive.
I've been looking forward to this game ever since it was announced for the Game Cube and I'm looking forward to it even more now that it's coming out for Nintendo's newest system.
IGN.com ran a great preview today, found here. Wired.com also ran a neat-o write-up on the game. Check them out if you want a bit more information on the game.
Here are some great video captures of the game (from the floor of GDC) as well. Looks great to me!