So far, it's great. It looks fantastic. I'm particularly impressed with the track side scenery, an often neglected part of racing games. It makes those especially long races a lot more enjoyable when you're driving past beautiful mountain vistas.
The Autovista mode is pretty cool. Basically, you can view and examine a few different high-end cars from every angle. They're rendered in extremely high quality and you can open doors, bonnets, sit inside, etc. You can also listen to Jeremy Clarkson give his opinion on each model.
There seems to be A LOT to do in career mode. Not sure if I'll ever finish it. Some of the additions seem a bit pointless (like driving around the Top Gear test track knocking down bowling pins), but some are great, like the traffic races (where you race on a track with loads of slower cars and have to pass out as many as you can).
Overall, it's a solid racing game. I can't compare it to Gran Turismo 5 as I haven't played it, but I haven't played anything better on the 360.
