I just bought Sonic & All-Stars Racing Transformed on 360. I already own it; it's a Christmas present for a friend, so he can join me playing it online.
I noticed that there are still plenty of copies left on 360 and PS3, despite it having been up for 10 minutes. If you don't already own it, get it! It's fantastic, and £17.49 is a fucking steal, seeing as it's only been out a week. Also, if you were planning on picking it up later, bear in mind that this is the limited edition, which has an extra track and character. Only the first print run of the game will be limited edition, so waiting will lose you in-game content.