My son is still using his over 5 y.o. MacBook Air. The machine was purchased when he entered the 6th grade. He carried it in a backpack for 3 years of middle school as part of the school's Laptop Program....talk about torture tested. Then, 2 more years of High School classes and still going strong.
My daughter got 4 trouble free years from her MBA in College. That machine is almost 5 y.o. and still operates flawlessly.
My MBA is only 3.5 years old, and it works like a champ. Easily, the best computer I have ever owned.
Screen might not be perfect, but damn, these are great machines.