The Canon EOS 5D Mark III offers a lot more capabilities and better performance than it's predecessors but despite a new sensor and new image processor, it's not so different on the basics meaning photo and video quality is what you'd expect.
Of course, the 5D Mark II is pretty great in those respects and a drop in the king doesn't necessarily a bad thing.
With a couple of exceptions, I really like the design of the Mark III which pretty similar to the Mark II.
My favorite aspects are the large lockable control dial which can double as a silent touch pad for adjusting settings during movie capture and the updated 100% coverage view finder.
The controls are extremely customizeable.
They are well designed and easily accessible interface.
Canon added a small programmable button to the top of the camera and the depth of field preview button, also programmable now sits near the grip for operation with your right ring finger.
Canon has updated the recording interface moving and consolidating the control for easier access.
While it's great with the mode dial now locks, it uses the center push button that they've used in the 60D in which I find a bit awkward and while I don't dislike the location of the power switch, it does routinely slip from off to on when moving in and out of my camera bag.
Incorporating Digit 5+ processing adds a lot of important features to the camera which includes support for UDMA 7 compact flash.
The camera now has dual CS SD card slot which is really a useful feature.
The Mark III also gets a dedicated headphone jack, time code support and 64 levels of audio control plus the wind filter.
One video disappointment, the camera only outputs the display view via HDMI so you can't get high resolution video capture that way but it's no doubt that the Mark III offers excellent photo quality.
The unprocessed images do seem to have less pronounced color noise than the Mark II and at mid-range high ISO sensitivities, images do look a little cleaner but at low to middle ISO sensitivities, I actually think the JPEG photos from the Mark II look a little better with more naturally deploying detail and fewer processing artifacts.
That said, the Mark III's JPEG do look fine, better than fine up through ISO 1600 and depending upon the scene and your needs, that can be quite good through ISO 6400 and the larger higher resolution LCD is much better for staging sharpness.
They still really need a third-party viewfinder for shooting video.
I would love to see a peeking feature which would help a bit.
Unlike the J800, the Mark III is no-brainer upgrade for 5D Mark II shooters but I think that's more of a testament to the quality of the Mark II than anything lacking in the Mark III.
It does have some important advantages over it's predecessor though including a much faster auto-focus system, improve video quality and controls and a fun more configurable feature set.
If those are important to you, it's definitely worth the price premium over the now reduced Mark II.
I'm Marie Grunan and this is the Canon EOS 5D Mark III.