I had an '05 S2000 and loved it. Had to sell it when we dropped down to a 2- vehicle household and vowed that it would be replaced by another ASAP. I picked up a 2006 with 3800 miles on it and life is good (again). I looked at Boxsters, Z-4's, SLK's (I do not consider the MX-5 to be in the same class) and still could not come up with a valid, logical reason to buy any of them. For the money, this is simply the BEST roadster out there. The drivetrain is as close to perfection as one can get. It handles great and is as solid as if it were milled from a piece of billet. If you are of average stature this car is very livable as a daily driver and is quite comfortable on extended road trips.
The engine is sweet and the transmission is an example all manufacturers should study to learn how a manual transmission should be made. Best Stock brakes on any car I've owned. Maintenance is real simple- regular oil changes. That's it. It IS a Honda. Overall build quality is impeccable.
Since the S2000 appears to be at the end of its model run it would be pointless to address any perceived shortcomings. Any additions to this car will just add unnecessary weight and detract from the beautiful simplicity of the total package. Save the gadgets for its overpriced competitors.