Here's an edited down chunk of a G4 podcast recording, splicing together all the moments where Morgan Webb expresses her distaste for Mario Galaxy 2's kid-oriented graphics. I don't completely agree with her but I know what she's talking about. I'm probably one of the few people who was disappointed with the original Galaxy--at around the Toy Time level I got the distinct impression I was being condescended to.
Still, from what I've heard Galaxy 2 is much harder than the first game, so it seems to be the presentation that bugs Morgan. I think that's just part and parcel to the Mario universe--it's a very childlike, innocent place because that's just how Miyamoto's mind works, he has a very friendly, optimistic outlook. I guess I'll find out when I pick up the game this weekend.
As to kids being able to handle a challenge, I agree with Ms. Webb. When I was a kid, N64 games cost upwards of $70, a heck of a lot of allowance money, so you played that new game to death until you absorbed it through your pores. Party minigames? Wii Music? Please. That stuff's for the old people, the Wii noobs who think they know what kids play. If kids could beat Mario 3, Contra and Battletoads in the 80s, today's generation sure can do it now with modern games that are just as hard.