Well, I've noticed the XBox having brighter colors in general, but I can still see why someone would call it "cartoony". Although, I prefer to call it beautiful.
It's largely the colours with that TG track shot, you're all used to seeing it all washed out and through the blue filters that the TG crew religiously use. Fiddle with the colour settings on your monitor, or run it through photoshop and you'll find it looks much better.