After owning the 5d2 for many years and now upgrading to the 5d3. All I have say is.
WOW
1. Auto ISO works FINALLY with minimum shutter speed settings. (ISO Priority)
2. Auto focus is unbelievable. Cutting down Lightroom cropping by 75% since I can now use all the focus points. It doesn't miss...
3. I can now put in two 32 gig cards in and shoot 30 minute intervals for video. Just that alone, will save me having to explain why I missed part of someones speech or just being nervous about when to stop recording.
4. Audio monitoring!!!
5. The Screen doesn't get fingerprints like before
6. I can't complain about the iso on the 5d2 but on the 5d3, I couldn't ask for anything more.
7. The metering is smarter which means less chimping and more shooting ( I should say less shooting).
Don't know how I will ever use the 5d2 again... 
This is after owning it only 1 day, so we shall see what other goodies I find in the future.




