After owning eight previous BMW's, I can honestly say this is my favorite. This car is probably too much for the street in most instances, but don't let that stop you from picking one up. Maintaing one of these cars is a bit more expensive (namely the high end tires), but with the maintenance programs that BMW now offers on their new vehicles this is less of an issue. Very quick, amazing handling, and probably the best brakes ever put into a production vehicle add up to a whole lot of fun every time you drive it. In the immortal words of Ferris Bueller "If you have the means, I highly recommend picking one up".
My car came equipped with the Xenon lighting package, which turns night into day. The seats and mirrors have a memory function that corresponds with the two master keys that came with the car. Very handy when two people use the car regularly.
Difficult to improve on the damn near perfect. Their are tons of companies that make after-market performance products for this car. You can go from mild to absolutely gonzo with this vehicle depending on how deep your pockets are (and how long you wish to keep your license!!!)