I just picked it up on Thursday, so as well I can't give a full review. Also I have yet to go online with it due to work. This weekend I hope to really dig into everything it has to offer, but here are my first impressions.
The speed is absolutely blistering, I find myself using the emergency brake quite often to spin around and go back to crash through something I saw but blew right past. Don't get me wrong, this is a GOOD thing for a Burnout game.
Personally I love the slow-mo crashes. My wife and I have some pretty good debates as to whether or not a person could survive a given wreck. The game will make you say OUCH after wrecks, or in my case yell expletives. Due to the speed of the game, you WILL end up crashing into things you didn't see coming. This is actually fun because it will make you jump due to the surprise factor.
If Showtime wasn't required for completion, I wouldn't bother with it. They would have been better off bringing back Crash runs from Burnout 3 and Revenge instead.
I guess my first impressions are if you are a fan of the series ( the PS2 titles anyway ) then this is a must try.