Bought privately when it had 7,000 miles due to sellers expecting twins. No major repairs in 104,000 miles of ownership - now has 111,000 miles. I now drive 47 miles one-way to work all highway and average 33 mpg using non-ethanol 87 octane fuel. Plan on driving until 250,000. No rust anywhere. I believe the great reliability is due to the 6th and final year of this body/design style. All kinks worked out.
Acceleration torque, 5-speed manual, responsive & precise cruise control, tight feel of the road.
Better design on hubcaps (noisy due to fittings) seems to be a common suggestion.
I purchased this car 2 years ago and I actually like it a lot. I do not speed excessively, my tire pressure is where it should be and it's recently been serviced, in town I get 14 mpg at best. I might have sold it, but it's been reliable for the most part.
Traded it in on a new '08 Altima last week. My '01 played a large role in my deciding to stay with Nissan. If you're looking for a rock-solid, reliable, and fun to drive used sedan, the Altima SE is one of the best. No major problems, just some small niggles (described below), every car has them. Very comfortable, fuel efficient (30 mpg on the highway, at least), great around town and for long-distance cruising. If you enjoy the act of driving, don't bother with the GXE or GLE... the SE is the way to go. It may not be the quickest in a straight line, but it'll surprise you in the twisties. Overall, I was very happy with the car, kinda hated to see it go. Highly recommended.
Tight construction, crisp sporty handling with SE trim level, subtly handsome without looking boy-racerish, 6-disc in-dash CD changer standard, great fuel mileage, comfortable. Only has 155 horses, but good strong torque makes it peppier that you'd expect. Cheap to own, reliable as the tides.
Had some problems with the rear suspension bushings creaking over speed bumps in the cold. When the cooling fan ran after shutting the car off, the keyless entry remote was pretty much ineffective. Never was able to figure out a fix. Could have used another 50 horses to go with the chassis... :)
I bought this car on 8/2001. So far, so good. The only repair has been the power windows (recall). Mileage is excellent up to 33 per gallon (combined). So far 65K miles and no brakes changed. It is very reliable, I love my car and my plan is to keep my car at least 6 years more. The only thing I do not like is the hubcups and noise from wind against the car.