Please please don't buy!
This is one if the worst games I've ever played racing or otherwise. It features tons of content which makes it feel like a must buy, but you'd be better off with almost any other racer. Here are some off the reasons not to get suckered. Only a fifth of the car models are new. The ones that are new look great but the rest look extremely dated. Track graphics are sterile and of intermittent quality too. The AI is non existent - any attempt to drive 'properly' is ruined by cars ramming into you and refusing to concede the racing line even though you've legitimately out manuevered them, slowing you both down pointlessly. There are tons of rough edges too. For a game that took this long to make it's ridiculous to have voice over drowned out by engine noise, an engine noise that drones on at the same pitch during all the post match menus.
But the completely unforgivable thing are the menus. I've had to wait up to five minutes for the main menu to load after a race (usually nearer one minute). Most of the menus take 30 seconds to load and there are a ton of menus. Restarting a license test involves around six menus.
The game doesn't look that great for the most part as most of the assets are copied from previous games. The driving is fine but the AI is horrible. The loading and menus make it almost unplayable.
Only buy if you've already got forza3, hot pursuit etc and have to have everything. (like me sadly.)