The K20D's performance is very good, although it's not as fast as some of its rivals. It has Pentax's newly improved SAFOX VIII autofocus system, with 11 focusing points spread widely across the frame. Nine of these sensors are of the more accurate cross type, and I was suitably impressed by the speed and accuracy of the system. The only camera I've seen recently with a better AF system is the much more expensive Nikon D300.
Shooting speed is also fast. In single shot mode it can take a picture just as fast as you can press the shutter button, at least two shots a second. There are two continuous shooting modes, a high-speed setting that captures three frames a second, but is limited to 38 shots in JPEG mode or 14 in RAW PEF mode, and a low-speed mode that can shoot at 2.3 frames per second but can carry on until the memory card is full. That may not sound too fast compared to the EOS 40D's 6.5fps, but it's fast enough for most purposes, and is pretty impressive when you consider that it is writing JPEG files that average around 10MB each, and RAW files of over 23MB.
Those huge file sizes translate directly into image quality, and here is where the K20D really shows its worth. Quite simply it produces the sharpest, most finely detailed pictures of any current semi-pro DLSR. Dynamic range performance is outstanding even without the Enhanced Dynamic Range feature, and colour reproduction is as good as ever. However it is not without its problems. I found that exposure metering was often inconsistent, and often under-exposed by as much as a stop. This isn't as much of a problem as over-exposure, and is easily corrected in RAW post-processing, but it really shouldn't be happening on a camera of this quality. I also noticed some inconsistency in white balance from shot to shot, especially at higher ISO speeds. High ISO noise control is very good though, with little sign of noise until 800 ISO, and perfectly usable images at 1600 ISO. Even shots at the 3200 ISO maximum are far from hopeless.
The quality of the supplied 18-55mm lens is better than most kit lenses, and produces good edge sharpness with little distortion, but it is a bit prone to chromatic aberration in the corners. This lens has been in use now for over eight years and it is beginning to look a bit weak by modern standards. If I was to buy a K20D (if only I could afford it!) I would buy it body only and buy the rather lovely SMC PENTAX-DA 16-45mm F4.0 ED/AL instead.
With the launch of the K20D Pentax is taking on the top players in the semi-pro DSLR market. It has a class-leading specification, with build quality, handling and performance to match, and has exactly the sort of features that will appeal to advanced amateurs and semi-professionals. The slight problems with exposure consistency are annoying but not fatal, and the breathtaking detail of that 14.6MP sensor more than makes up for it. The K20D is a very accomplished camera and exceptional value for money.