Still got my lifetime AAirpass. But it's not unlimited. Bought it in 1994 and the plan I paid for was 55,000 miles per year. Price was about $155,000 at the time. Had to look at where I (and eventually AA) would wind up in the cosmos of time. For one thing, I work hard as a surgeon (still do) and can only fly so much. Also, at the time, the highest elite level was Plat---exp did not exist. So 55,000 mi/yr seemed about right for me, individually.
The other thing was that one could roll over miles that weren't used in a year to subsequent years. So right now I'm sitting on 500,000 + actual AAirpass miles to use. Obviously I use other carriers as the need arises. Back in 1994, AA had a busy hub in SJC. No more. Also, the "lifetime" of the AAirpass could well be AA's, not mine. At any rate, they're still honoring it during bankruptcy.
UA had a competing plan (still does) called Pass Plus and I contemplated getting that, because AA gave mileage credit for both the companion and the AAirpass flyer to the AAirpass flyer's account---UA did not. I bought a couple of 5-yr Pass Plus plans, though. It's hard to argue with UA's dominance of air traffic in the SF Bay area. And, IMHO, the single most transforming event in the airline world will always be Sept 11, 2011.
So I have had a good experience with AAirpass. Never felt that I was gaming the system like some of the cases discussed here. In fact, I've never done a mileage run in my life. Have got 7 mm, including credit card bills, on AA in my time. Hope the pass continues to work.