Personally, I've never experienced any problems on any of our aircraft. The Triple does seem to be rather unpopular, though. Don't know why - I'd gladly never set foot on a Jumbo again in favour of all 777 flying.
I remember KLM also experienced problems when they took their first 777s last year. A number of their crew actually fainted during the flights. The problem was said to be worst by Doors Three for some reason.