Proper cars, proper mayhem, proper challenge.
But it's much more than that, while at its heart this game is a racer with weapons, winning is just one component of the game. You need to be a skilled driver in a variety of vehicles, you need to be able to use the power ups well and choosing the right car makes life so much easier in each race.
To get ahead you have to meet each boss's demands - which range from the simple (complete a particular course through specific gates) to more complex (dodge specific power ups). You've got to be good at it all to unlock the special stuff.
The racing is intense and impressive - it sucks you in and makes you want more...even when you come stone cold last. Sometimes those challenges fall by the wayside when you're after a win - good for your ego, but bad for your progressing. The game plays you very well, so even when you nail a top 3 position or complete a certain challenge, chances are you'll want to come back to improve on something.
Everything in the game looks very slick - the menus have an urban neon feel to them and the presentation feels like a high-octane TV show.
There's very little wrong with the game - the limited ability to change your controls is a niggle, but if you're familiar with driving by WASD (e.g. GTAIV, JC2) then you should be able to get along just fine. It still feels like the game needs some optimising - it's very pretty but I've had the licensed music result in intermittent lag while racing (Admittedly I didn't like the music and turned it off, so the situation was win-win).
In short this is a good looking, fun game. A game that's easy to get into, but hard to master.
Late addition: This game works much better when you use a 360 controller (The only one available) - the keyboard's lack of sensitivity makes some races ridiculously hard.