Downloaded it while I was at school, came home to try out the bikes...
Good:
To some people, it's like an entirely new (though short) game.
Bike is significantly easier to avoid crashes with.
Time of day is done exactly as it should have been.
I saw a burger king ad on a billboard as I was crashing. :D
New online crap, though I haven't been online.
Wheelies! :D
Bad:
VERY little you can do with cars can you do with bikes - this includes jump cam, etc.
No ragdoll. D:
The crashes for bikes are horrible compared to the crashes for cars - they aren't deformable at all.
I'd say it's definitely an improvement, and essential for Burnout Paradise owners, but it could have been better if they'd spent more time on it (though the time spent would have been significant I suppose).