This car has exterior and interior rattles and lackluster acceleration. However, with all its faults, it's the most reliable car I've ever owned, and it's also been very inexpensive to maintain. It still averages around 27 miles per gallon, and that's not bad considering it has 210,000 miles!
Reliability. Not a very exciting car, but you won't have it in the shop more than you have it on the road! =)
The improvements have already been implemented in the newest Altimas, although the gas mileage has gone down.