I had an '02 E46 M3 before getting my new '09 E90 M3. These cars are quite different in their personality, but both are great. The E46 actually feels more like a sports car while the E90 feels more like a grand touring car. The power from the E90's V8 is amazing and almost effortless. I ordered the M-DCT transmission and am absolutely amazed. The shifts are super quick and super smooth. It feels like the shifts from BMW's auto transmissions. While I tend to be a sporty driver, I have to admit the M- DCT tranny is so good, I often leave it in full auto mode. All in all, I love it!
This car is much more comfortable than the previous M3. The additional leg room makes the car much more livable. The V8 power has much more low end grunt than the previous inline 6 (3.2L). The exhaust note is great, but not overly loud. The brakes are phenomenal as is the handling.
Fuel economy is bad (17mpg). With such a powerful engine, a taller gear could improve highway fuel economy (20 mpg). The steering is direct, but it is a touch too light and gives less feedback than the previous M3. The cup holders are chintzy and the glove box will barely hold a pair of gloves.