Conclusion - Pros
Smooth clean images with good color and tone, not as crisp as we would like
Robust body with dust and weather seals, high build quality
Accurate and fast auto-focus
Unique exposure modes; sensitivity, shutter/aperture priority, hyper program
Selectable program lines; Normal, Hi speed, Depth and MTF (lens sharpness)
Good range of image parameter adjustment (-5 to +5 for each)
Dedicated RAW button a useful addition
Selectable RAW format (PEF or DNG)
Unlimited continuous shooting in JPEG mode
Occasionally useful 'digital preview' allows you to take a test shot which isn't saved
User definable Auto ISO (set minimum and maximum ISO)
Good built-in flash metering
Large and bright Pentaprism viewfinder (0.95x magnification)
In-camera Shake Reduction system offers some advantage in low light
Dust reduction by anti-static coating and optional sensor 'shake'
Mirror lock-up implemented as part of the self-timer
Function menu for quick access to important settings (although hard buttons are better)
Large, bright and high resolution LCD monitor
Good battery life from high capacity Lithium-Ion rechargeable
Proper hinged doors covering the connectors (not the cheap rubber bungs)
In-camera RAW development and image retouching (B&W, Sepia, Soft etc.)
USB 2.0 Hi-Speed interface (with mass storage device driver)
Value for money
Conclusion - Cons
In-camera image processor unable to deliver crisp sharp edges, better to shoot RAW
About a third of a stop less highlight dynamic range than the competition
Slightly inconsistent continuous shooting rate (although always around 3.1 fps)
Would have been nice to have hard buttons for White Balance and ISO sensitivity
ISO not displayed on viewfinder status line or top LCD status panel
Turning up sharpness setting doesn't deliver crisper edges
Average automatic white balance performance, still very poor under incandescent light
Flash must be raised for AF assist (although AF works even in very low light)
Color space selection buried in custom menu
Overall conclusion
My first impressions of the K10D were very positive, a well designed and robust body with a clearly extensive range of manual functions and a fairly logical control layout. The positive experience continued in use with the large, bright Pentaprism viewfinder, fast auto focus and short lag times. Menus and playback are equally as snappy although I personally found the connected 4-way controller less easy to use than the K100D's four separate buttons.
The K10D's advantages over the competition are fairly clear; dust and weather seals, in-camera Shake Reduction which delivers at least some low light advantage with all your lenses, selectable RAW file format (although both are 10MB+), user definable Auto ISO, digital preview and those unique sensitivity-priority and shutter/aperture-priority exposure modes. It's a camera which should provide more than sufficient 'gadget satisfaction' for even the most demanding shutterbug.
When we reviewed the K100D we thought Pentax had got their image processing just right, however the single element of the entire K10D equation which left us scratching our heads was just that. Either a poorly implemented demosaicing algorithm or a strange choice of sharpening parameters means that while the K10D's JPEG images have plenty of 'texture' they can lack the edge sharpness we're used to seeing from semi-pro digital SLR's.
Pentax may well have been aiming for a smooth film-like appearance but I at least feel that the inability to tweak this out by increasing sharpness is a mistake. That said it's unlikely you'll see this difference in any print up to A3 size, it's a 100% view thing so you have to decide if that's important to you or not. To get that absolute crisp appearance you'll need to shoot RAW, and use Adobe Camera RAW or another third party converter (as the supplied converter produces similar results to the camera).
With the criticism out of the way we return to the K10D as a 'photographic tool', something it does very well. It's a camera you get used to very quickly and never really leaves you searching for the correct setting or control. It's also a camera you can grow into, the unique exposure modes are both creatively interesting and useful, a range of options such as this encourage you to experiment. At just under $900 it's a very strong proposition, so despite our reservations about the slightly soft image processing the K10D just achieves a Highly Recommended.
Detail (D-SLR) Rating (out of 10) Build quality 9.0
Ergonomics & handling 8.5
Features 9.5
Image quality 7.5
Performance (speed) 8.5
Value 9.0
Highly Recommended (just)
For those of it wishing to see sample they include very many.
http://www.dpreview.com/reviews/pentaxk10d/