Finally Pentax has got its act together and produced an excellent camera for the enthusiast and semi professional markets. If you have been holding out for a quality digital body from Pentax and haven't been tempted to move to the other four major brands, now is definatley the time to make the switch to Pentax digital.
Almost all Pentax K mount fitting lenses from your old Pentax 35mm outfit will work well with this camera, despite some minor limitations in manual aperture selection and a focal length increase of x1.5 across the board. For example your 50mm lenses will become a useful 75mm portrait lens.
The camera is as solidly made as it's rivals from Nikon and Canon, built with over 70 weather seals against the elements. Not since the Pentax LX has this quality been present on a Pentax camera body. The current range of digital specific lenses is somewhat limited at present, though this is due to change over the course of the year as new lenses from Pentax, Sigma, Tokina and Tamron are all in the pipeline.
The ease of use, the build quality, features and performance make this a formidable challenger to the dominance of Nikon and Canon in the semi pro / enthusiast section of the market. Time will tell whether Pentax will now reassert the place it once held in the 1970s and 1980s as a class-leading manufacturer. With the K10D it has a very good chance indeed.