I have had this car for twelve years and have enjoyed it very much! As long as you take care of it, it should last you a while. Mine is a little shaky once I get past a certain speed (over 50) but nothing unbearable. Very good quality for a 2006.
You know that a car will only last as long as you have followed the proper maintenance schedule for the car. I bought this car in 2013 and the previous owner did NOT take care of it. Just dumped it as soon as things started to go wrong. I checked all the oils, fluids and filters and they looked horrible...But the good news is that my son is now driving the same car to college three years later and it continues to performs PAST my expectations. The Altima is now 16 years old and he plans on driving it another two years.
Update12/2016 As with any older car there will always be on-going maintenance to do. Just recently, I noticed a small leak in the upper radiator hose connection to the engine block. That gasket after 16 years in finally giving out. So I will be replacing that gasket and the thermostat at the same time. Since it is December I will also be changing the oil again. Temperature is getting down to 0 degrees...brrrr.