It is basically a better version of World Tour. I just finished playing it for over an hour and had tons of fun so far. The Mii free style is way better than before and the new DS connectivity makes this game that much better. So far I am not extremely happy with the track list, but I can't expect them to have every single song I like on their.
I really recommend everyone who loves this series to buy this game, you'll be happy because it is definitely worth it.