I just got a Wii and this game a few days ago for my mother for her B-Day coming up in a few days.
I played SMG a couple times probably just 4-5 hours total, and yeah it seems pretty good. I like it. I bought a GC late that gen and Mario SS was one of the games I wanted and for some reason I couldnt get way into it... SMG seems like the greatness a Mario game should be.
Anyways yeah only played it a couple times.... got like 5 stars... Though I want to and know I will play be playing it anyways, I got it for my mother so I really just wanted to play it enough to see if I think it is some thing she could play without having some problems turning her off from playing.
Anyways all in all Im happy I got SMG for first game for the new Wii I got ofr my mom. I think she will love it and have a bunch of fun. And the game itself from what Ive played really seems great. IMO judging from all the vids and reviews of different Wii games on the net, Mario Galaxy seems like the best choice for any one to be the first game they purchase.