I looked at the Canon 350 and 400 but their auto focus sensor system was not as advanced as the Pentax and the body was awkward to hold. The K100d may have slower AF but it locks on accurately with few mistakes. Also Canon and Nikon required expensive lenses if you wanted shake reduction. The Sony A100 was my other option but once again, the Pentax felt better ergonomically when I picked it up and the price was way better. The Nikon D80 is a great camera but was much more expensive.
I've managed to acquire a K100d body, an SMC 18- 55 zoom, an SMC 50- 200mm zoom and a 50mm A 1.7 prime lens(used) for about CA$1000. I think that's a selling point right there. Also the fact that lenses are so available and of such good quality for the price pushed me to Pentax.
Now, there are a few negatives I have found which I think are common knowledge now. Auto white balance in not too accurate in incandescent light. I set it manually when indoors. The ISO 200 default with exposure compensation when auto ISO is set is a bit strange, the lack of ISO readout in the viewfinder too, and the fact that the ISO settings don't have a hard button to access them quickly are a few. Most of the time I don't use Auto ISO so the ISO 200 thing is not an issue. After two months however, I am getting used to the controls and these limitations are minor and easily worked around.
As for the 6 mega pixel limitation I haven't really printed that much so I haven't run up against the limitation. The major advantage to me was to move from P and S to DSLR. I must say that in my point and shoot days, my 5 Mpix Casio compact never came close to my 3.2 Mpix Olympus C3000 which still to this day has the most faithful colour reproduction although it's rendered useless due to a built in hard coded software bug.
I do my fair share of cruising in camera stores and have no regrets with my K100D purchase. Maybe in a coupe of years if I outgrow it, it will become my 2nd body and the to-be-announced K2D or K1D will become my primary body.
I have 2 friends with beautiful and very expensive Canon systems a 5D and a 30D but their heavy cameras are usually back at home when they talk about their systems. My k100d because it's easier to carry and less obtrusive is usually on my shoulder.
Not to mention, I kind of like the "we try harder", 2nd tier status of Pentax. There's something inherently efficient about getting the same or better results with a camera system costing so much less
.