Just a few observations - some rarely metioned and others confirming other people's findings.
The not so good?
- focus points not being LEDs; dreadful, dreadful, dreadful move!
- ISO 100-400 performance no different, even a bit noisier (see later positive comment)
- No lighter (I'm getting older!)
- Very markedly fewer images on a 32Gb than the 5DII
- no measurable improvement in colour accuracy - more testing needed
The good
- noise cleans up better and, at high ISOs, leaves a lovey grain in LR4
- focus far, far better. Even my old 85mm 1.2 MkI is significantly better
- Inbuilt levels for viewfinder and LCD ; oh boy - a dreamy feature for me
- extensive button remapping
- Image stacking - finding new ways to use this all the time
- white balance appears better in my few test scenarios
- High ISO performance - sooooo goood!!
- auto-ISO ; very usable indeed
While I listed a fair few negatives, it does actually feel like a very worthwhile upgrade. The indicator? My other half already wants her 5DII changes 


