This is a tough, compact and very well-thought-out camera, with genuinely useful features that its rivals don't have. But it does have two significant drawbacks.
Cruder than rivals
The first problem is that the K-7 feels quite lumpy and crude compared to rival cameras from Canon, Nikon and Olympus, although it does have the edge over Sony's dSLRs.

Perhaps the main reason for this is the lenses. Until Pentax introduces a smooth and silent autofocus system across the board, like Nikon's Silent Wave Motor or Canon's Ultrasonic Motor, it's always going to be at a disadvantage.
The second issue is that there are quite a few lenses in the Pentax range, but it doesn't have the same depth or quality as Canon's and Nikon's. Amateurs and enthusiasts might not be bothered, but professionals need to think long and hard about investing in a system rather than just a single camera.
Conclusion
The Pentax K-7 is a great camera, but you've got to find some decent lenses to go with it. Don't forget that, for roughly the same price, you can get the Canon EOS 50D, and, if you up your budget, you could be looking at the Nikon D300S.
Edited by Charles Kloet