Picked the game up from Tescos for just under £30, and today I've also finally set up a permanent internet connection for my 360 and purchased 3 months of Xbox Live, so I can finally use the online features of my Xbox fully once more.
I'm liking the game a lot so far, pretty much the same as Mario Kart only I can play it on a console I prefer with a cast that I also prefer (always been a Sonic over Mario kind of guy)
Beat the first two cups on Beginner (Beginner/Advanced choices seem odd - I'd say that I should be somewhere between!) and unlocked half of the tracks so far, which I've played with my girlfriend. I was surprised, she's not really into games but she's picked it up well, even beat me a few times.
So far I've unlocked a few extra characters as well, and I'm loving all of their different All-Star abilities.