Bought the car slightly used, and I've only had two minor problems with it, both outside of warranty. First, the radio, which Nissan replaced, rather gave me a gift certificate to Circuit City, which turned out to be a better deal. Second was the CPI, which Nissan fixed at a highly discounted rate. The car has been a true workhorse for me. Multiple trips almost the length of the East Coast and one cross country trip. I've put a little aver 80,000 miles on the car in less than 4 years. Other than the radio and CPI, I have yet to do more than just regular upkeep on the car, and I am very hard on cars. I'd definitely recommend the Altima to a friend, and would definitely buy another.
Comfort, ergonomics, responsive, fun to drive, over all look of the car.