So this is the spec (lifted from canon) and just the interesting bits for video (mostly):
The Canon EOS 5D Mark III Digital Camera is a full-frame 22.3MP DSLR featuring exceptional still image and move recording capabilities. Integrating Canon's new DIGIC 5+ Image Processor and 14-bit A/D conversion, this camera is able to produce superbly detailed imagery with immense low-light sensitivity that is further aided by an extended ISO range up to 102400. Image quality is further enhanced by the new 61-point high density reticular autofocus, including up to 41 cross-type AF points and 5 dual diagonal AF points for ensured sharpness. iFCL metering works in conjunction with the AF system and uses color information from scenes to produce accurate exposure readings using a 63 zone dual-layer metering sensor. HDR and Multiple Exposure modes provide greater creative opportunities and help you to reduce the amount of post-production time needed to produce high quality imagery. The 5D Mark III is also capable of recording full HD video with manual exposure control and in multiple frame rates, including 1080/30p and 720/60p. Still images can also be recorded up to 6fps.
Image review is possible using the 1,040,000-dot 3.2" Clear View II LCD monitor, which features a high-transparency, reflection resistant multi-coating for adequate viewing under bright conditions. The Intelligent Viewfinder also integrates a superimposed LCD providing you with exposure information and features a 100% field of view.
A highly durable magnesium-allow body surrounds the components and offers increased dust and weather resistance. An updated EOS Integrated Cleaning system also helps to reduce and remove dust within the camera body. Several of the physical controls on the camera body are fully customizable for a more efficient workflow and more convenient handling scheme. Dual CF and SD memory card support also increases the compatibility of the camera.
- 22.3 Megapixel Full-Frame CMOS Sensor
- A newly designed 22.3MP full-frame CMOS sensor is incorporated into the 5D Mark III providing you with highly detailed, rich images with a maximum resolution of 5616 x 3744 pixels. The sensor is also features a high S/N ratio and larger individual pixels for increased visual depth and cleaner looking images. A new photodiode structure and increased photoelectric conversion rate also helps to improve the overall sensitivity of the sensor, resulting in a reduction in image noise and improved high ISO performance.
- DIGIC 5+ Image Processor
- Processing speed and power are increased to promote significantly greater overall performance and response from all aspects of the camera. New algorithms are incorporated in order to promote better noise reduction for higher ISOs and chromatic aberration compensation. The increase in processing speed also helps to improve the continuous shooting rate, bringing it to 6 full-resolution frames-per-second.
- 14-bit A/D Conversion
- The 14-bit signal processing helps to improve the quality and gradation of images by producing more natural, smooth-looking results. An increased ISO range is also provided, from 100 to 25600 in standard modes and 50 to 102400 in expanded modes. The ISO range can be controlled and customized depending on the user's preferences, and additionally an auto ISO mode can be employed. This extended sensitivity range helps to counter frequently changing and difficult lighting situations and significantly minimizes noise when photographing with even the top-rated sensitivity.
- 61-Point High Density Reticular AF
The newly designed 61-point autofocus interface helps to ensure
critical focus no matter how complex or difficult the situation is.
Featuring up to 41 cross-type AF points (with f/4 lens support) and 5
dual diagonal AF points (with f/2.8 sensitivity); this AF system is
highly accurate and extremely low-light sensitive.
The dedicated AF menu tab permits quick and easy access, eliminating the need to navigate through settings menus in order to modify your AF settings. Autofocus point selection is broken up into 6 different methods-Spot, Single Point, Single + 4 Adjacent Points, Single + 8 Adjacent Points, Zone Selection, and Automatic AF Point Selection-as well as a dedicated AF configuration tool for control of AI Servo AF III tracking parameters.
- EOS HD Video
Full HD video recording is supported in multiple formats,
including 1080/30p, 24p, 25p; 720/60p, 50p; 480/60p, 50p. While
recording video, a 4GB automatic file partition is employed in order to
gain longer continuous recording times, up to 29 minutes 59 seconds.
Both All i-frame and IPB compressions are supported as well as the
standard H.264/MPEG -4 AVC codec. Embedding the time code is also
possible for greater convenience when recording with multiple cameras.
Video performance is further enhanced with the ability to manually adjust your exposure settings and audio levels while recording. By employing Live View, you can view your recording on the LCD and make settings changes with a dedicated menu tab on the fly. The DIGIC 5+ processor also dramatically improves video response times and helps to reduce color artifacts, aberrations, and moiré.
- Rugged and Efficient Design
Constructed from magnesium-alloy, the 5D Mark III features a
toughened housing that provides enhanced dust and weather resistance.
Its ergonomic design also produces an intuitively navigable interface
with an emphasis on lessening hand strain and increasing functionality.
Handling is simplified and natural with this body due to the
incorporation of customizable controls, an internal headphone terminal,
and dual card slots supporting both CF and SD memory cards.
A newly designed shutter is equally as durable and has been tested up to 150,000 cycles. The lightweight, carbon fiber blades also provide support for the increased 6fps burst rate.
The body construction also features extensive gasketing for maximum dust and weather protection, even at connection points around the lens, hot shoe, and memory card slots. Further dust protection and removal is aided by an updated EOS Integrated Cleaning system that uses a vibration-based dust removal process.
Probably hehe need to see it and test it out first but it would make a great first camera and my lovely 7d will be kept as a second camera back up :-)