I have to agree with FOMere2eternity.
I have just got home from a disasterous trip Tokyo-Frankfurt-Toronto-Tokyo with the last two legs with AC.
In Frankfurt the flight has been overbooked by AC and although I checked in 1.5 hours before the flight and had a valid ticket I was bumped and re-routed via London. Arrived in YYR some 6 hours later than I should have. (Fat lot of use my Lufthansa Star Alliance ticket was on a code-share!)
For the final leg from YYR to Tokyo the flight was already delayed by two hours when I checked in. After we boarded there was a fiasco as we were all told to exit the aircraft immediately, leaving our carry-ons on board. We finally departed 6.5 hours after the scheduled time on a replacement aircraft.
Yes, I guess the second problem could happen to any airline but after hearing numerous stories about AC during the trip I will avoid them in future.
Shabby to say the least!