I've driven many sports cars and this is my favorite ever. The Porsche Boxster has it beat a bit on handling, some muscle cars (such as the GTO) have more horsepower, and a few have more torque. But for ~$30k you get more from the 350Z in all those categories than you can in just one category from many cars that run $50k+. And it's such a gorgeous car with a unique look. Pictures can't do it justice -- you have to see it to appreciate the look. I even like the interior a lot, which some seem to complain about. It's compfortable, well-laid out, the gauges move with the steering wheel tilt (first time I've seen that), and the textured surfaces are both interesting and easy to clean.
The sound and feel of the engine (oh god), the look and style (what a head- turner!), the handling and comfort of the ride (yes, it's comfortable, and it's a sports car, go figure), and the interior layout and features.
Better gas mileage would be nice in these days of $3/gallon gas, but I've been getting 16-20mpg in the city with a fairly-heavy foot. I'd also like the cig-lighter outlet to stay on when the key is off to allow charging things, but this is trivial. Just felt like I had to complain about something.