I picked it up today. In short, I played the PS2 one a few months ago knowing I'd end up buying the Wii version. The only reviews I read online complain about the controls, but there are two things to this: 1) The Wii remote controls really AREN'T bad at all. 2) You have the choice of using the Classic Controller or GC controller if you want. I haven't tried either yet though because I was fine with the Wii remote. I played all the way through Konquest mode (that's my FOURTH TIME including the 3 times I went through it on PS2 and I'm still not sick of it) and really did the same as I did on PS2. The change in controls really doesn't make a big difference on the difficulty. It's a little more intuitive somehow to do moves but maybe I'm just noticing that because my wrists are going into the random moves I decide to follow up with.
Motor Kombat is A LOT more fun with the sideways Wii remote controls. It's kinda like ExciteTruck how it handles. I only played one course so far though.
Anyway, that's my brief review for now. If you have any questions about graphics or whatever else, post them here and I'll try to give you an answer.
In short, I'm totally totally happy with it. Lived up to the expectations I'd had for it since milking the PS2 version a couple months ago.