I've only owned my MBA for a few months, and it's been rock solid so far.
Our household has 3 macbook pros, 1 imac, 1 macbook air and 1 mac mini. The one problem I had was a warranty logic board swap on one of the MBPs. My son owns a 2008 MBP and that also had a logic board swap early on in it's life, but had been running strong ever since. It recently received an SSD upgrade to lengthen its life, so to speak.
Having been in IT since 1984 and been exposed to quite a bit of computing hardware, I've found these apple products to be on par with or ahead of the rest of the vendors regarding product reliability. I don't mind paying a the premium price, as in my mind it's been worth it.
$0.02 worth.
Ditto for me 2
2008 MacBook Core 2 Duo 2.4/4GB/500GB never bought Apple Care and bought this new, still running strong Zero issues. Can use a new battery but have not purchased on yet.
2010 MBP Core 2 Duo 2.4/4GB/320GB Bought AC never used it nothing wrong still going strong.
2012 MBP i5 2.5/4GB/240SSD no AC and now out of warranty, use it all the time, no issues.
We are very careful with our Macs and iPhone's in my house however had a few iPhones go bad under warranty, but no biggie as they were replaced.