The one time I experienced a serious problem on AC longhaul (LHR-YOW 767, aircraft malfunction on climbout, return to LHR with equipment standing by), everyone at AC was terrific. The captain and FO toured the cabin after touchdown to answer questions, and when we finally reached YOW hours late, I was met on the jetway with hotel / food vouchers and a BP for a new connecting flight first thing next morning. I was truly impressed, as day-to-day anecdotal coverage of AC, here and other places, is so scathing when it comes to customer service and service recovery.