So last month I sent my 5DIII to Canon, right before my warranty expired, to have them insulate the top LCD for the "light leak" advisory. The camera came back from Canon better than new and I was extremely happy with their service.
I'm not sure if it's a placebo effect, but I feel that my photos come out better with the right exposure. I took the camera out to the same location under clear and bright sunny skies, using the same lens, and I see that I no longer have to use exp compensation. I leave it at 0 and my photos come out looking correctly exposed. I was a little disappointed when compared to my 5DII, seeing that a lot of my photos seemed to look about 1/3 stop under exposed. I simply figured that it was due to the new metering system.
Maybe it's just me, but I feel that when taking photos while the sun is directly above you, the LCD light leak is somewhat affecting the metering. I haven't tried proving it side-by-side, but my exposure now seems similar to my old 5DII without having to compensate.