Pentax hasn't skimped on performance either. The K-7 starts up and is ready to shoot almost instantly, and can take a picture in about half a second from a cold start. It has a newly-developed 11-point wide frame autofocus sensor, with nine more sensitive cross-type sensors towards the middle of the frame, and it is extremely fast. Without having the rival cameras on hand for a direct comparison it's hard to say which is quicker, but suffice it to say you won't be waiting around for the K-7 to focus. Its low-light focusing is also extremely impressive, and since it also unusually includes an AF assist lamp separate from the pop-up flash, it can also take photos in total darkness.
In live view mode the K-7, like most other live view DLSRs, is limited to contrast detection AF, which is not as fast or as reliable. It is still effective, but I found that it was usually a better idea to pre-focus and then use the live view to compose the shot.
In terms of shooting speed, in single-shot mode it can shoot as fast as you can press the button. In continuous shooting mode it can manage 5.2fps. This is a little slower than the EOS 5D (6.3fps) and Nikon D300 (up to 8fps), but it is slightly faster than the Sony A700 (5fps). However it can maintain this shooting speed even in Raw + JPEG mode for up to 10 frames. In JPEG-only mode it can shoot 40 frames before it has to pause for breath. It can also shoot at this speed in live view mode with the mirror locked up.
Another major improvement for the K-7 is the sensor-shift image stabilisation system. Pentax has been using this system for a number of years, and the K20D's IS system performed very well, but the K-7 is simply incredible. I was able to take shake-free shots at shutter speeds as low as 1/8th of a second using the 18-55mm kit lens, vindicating Pentax's four-stop claim.
Also improved over the K20D's already impressive performance is the image quality. The benchmark for IQ in this class is the Canon EOS 50D, and in my opinion the Pentax K-7 matches or surpasses it in every criterion. It produces roughly the same levels of high-ISO image noise, i.e. not much, and has superior dynamic range and colour depth. The overall level of detail is excellent, and exposure, colour reproduction and focusing were reliably accurate even in extremely awkward lighting conditions. All in all, a very solid performance from a camera that has proved to be one of the highlights of the year, and arguably the best APS-C camera currently available.
The Pentax K-7 is a superb camera, and really puts the cat among the pigeons at the top of the APS-C DSLR market. It has rugged weatherproof build quality, superb handling and offers every creative feature you could possibly want and more besides. Performance and image quality are a match for anything else in its class. It's a tempting package for any keen amateur or semi-pro.