I find the ambient cabin noise inside a B777 considerably noisier than the A330/340 family. I dont know why this is.

Another problem with the 777 is the cabin aircon. Sometimes sitting in the middle rows can be like sitting in a fridge, whilst the window seats can be a couple of degrees more comfortable. Have noticed this many times and therefore never sit in this area if I can help it. I have observed (from the fringes) complaints from other passengers feeling the cold.