I've had the lost luggage nightmare happen to me a few times. The worse was in Tokyo. I did not get my bag for 3 days and when it finally arrived it was a mess. The clothes were stained and when I tried to get an explanation I was talked around in circles. I finally gave up.
Interestingly enough I just arrived back home tonight from Denmark with a connection through London. My one bag had a PRIORITY tag attached and that usually means it comes shooting out to the carrousel quickly. It didn't. My flight was a completely full Boeing 777 so lots of people and lots of bags. I waited an HOUR!!!! I was convinced they misplaced it. Then I saw it. It was literally the 3rd last bag to arrive. I was steaming mad up grateful it arrived.
Anyway, gripe, gripe, gripe.