It looks good to me (graphical wise), and it looks like a lot of fun.
Graphically, I think this will appear better than MKWii, because there is a lot less going on.
MKW has some beautiful scenery though, and this doesn't look like it will have that. It is a bit more Mario Party - esque.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS