YMMV!!!!
I for one got AppleCare for my 2011 MBA about 6 months after my purchase. I got it when cash wasn't so tight and to have just in case (purchased with student discount). However, it REALLY depends on the Apple Store you go to to get the repairs done. I had a recent problem with the display and hinge (totally my fault), and took it in to get repaired. They ran through the run-of-the-mill questioning and once they saw my issue, checked to see if I had apple care. Once they saw that I did, they said they would replace the entire display for free. I agreed knowing the only cosmetic damage my MBA had sustained was a slight dent on the back of the hinge near the display. Got it back a few days later and it was practically brand new (and even got a bonus: the samsung display to replace the lg on in it originally). While I was waiting to pick up my MBA, I noticed about 85% (rough estimate here) of the people in the store for repairs were getting free repair work (if not replacements) done if they had apple care, regardless of the damage done (one grandpa said his grand daughter got a hold his iPad and it was no longer working). So again, I stress, YMMV. You will get a pretty even split here on MR saying to buy it/not buy it but the majority that purchased it for notebooks seem to be pleased by their purchase/service