What do I think of the Boxster S?
I think it is one of the best sports cars I've ever owned, and that company includes not only my NSX, but a '93 Viper RT/10, a '96 Viper GTS, a Pantera GT5, an '88 Porsche 930 Turbo Cab, a '98 Porsche C2S, etc. It is an incredibly well balanced machine.
There's a reason most car magazines tout the Boxster S as the standard by which others are judged.
The one thing I'd say though is that it is best to buy a Boxster S used, if possible. I did buy new and got a $6880 discount (albeit in January of this year with snow on the ground and the economy in the dumps from 9/11). My '02 S listed at $59,380 and I paid $52,500. Used '00 S's are bringing only about $40,000 right now, making it a very nice car for the money.
Performance and handling are very comparable between my 22,000 mile '91 NSX and my Boxster S, but the Boxster S has a bit more low end torque than the NSX.