I've paired mine to a 5D MkIII and found it a perfect partner. It's similar layout makes it very easy to change bodies without having to think buttons again. Mine is fantastic, it took a short while to get used to it and get the settings to the optimal for me but now it's set it gives me great results. There was some AF problems with the first ones out, mine came with the firmware version of 1.0.2 and I've now updated that to 1.0.4 but I've not had any AF problems and my keeper rate is up above 90% out of around 5000 shots and most of the bad ones have been user error. I paired the 7D MkII with the new 100-400 L II a few weeks ago and the end results of this is brilliant, sharp as a tack, and compared to the two 7D MkI's I had the difference is like night and day.