I had a 2000 Boxster for 3 years before purchasing my Z4. It is Toledo Blue w/ tan interior. Sports package, chrome eliptical wheels & SMG. I would have preferred the 6 speed manual - but my wife wanted an automatic. SMG seemed like a good compromise. It took a while to get used to - but now we both enjoy it. The main complaint is that it is not BMW smooth in the automatic mode. However - I am loving the paddle shifters! The greatest surprise is the gas mileage. I easily get 23-26 in normal day to day driving (not taking it easy on the take offs) and 27-31 on long highway trips!
Same HP as Boxster - but much quicker. Great gas mileage. Paddle shifters. Excellent stereo - easy to enjoy at high speeds with the top down.
SMG - too difficult to explain to valets! Must park the car myself. Front airdam - although it looks great - is so darn low that I must come to a complete stop before going up my driveway and must go under 5 mph over speed bumps or SCRAPE.