I purchased this car in 2000 with 30,000 miles on it. About 3.5 years into having the car, the check engine light went on and stayed on. It doesn't really give me a problem and it goes off in the winter and back on in the summer. I've had to replace a lot on this car though. I've replaced the brakes about 4 times, the fan belt twice, the starter once, the fuel pump once and the MAP sensor once. I don't know if the car is garbage or if I just drive it hard. I do know that I wouldn't buy another Nissan Sentra, it served it's purpose at 19 years old, but now being 26 I've grown tired of it's lack of power and size. It's now up to 108,000 and when it dies there will be no more repairs.
Gas mileage is pretty good, I go through 10 gallons in one week but that involves traveling 15 miles to school, then 15 miles home, then 2 miles to work, then 2 miles home. I do laugh at all of the SUV owners when I'm filling up though.
Better sound system (I had to have my own replaced), more pick up, bigger trunk and just make the car bigger in general.