I think it dependes on what you want from a camera. I started with a K100D Super back in April this year, and it was a great piece of kit, but I moved to a D300 instead because I wanted something a bit quicker at focusing, a bit more MP and better/quicker glass for motorsport.
I have the K100D Super with kit lens and a Tamron 70-300 and found it a great introduction to D-SLR's. Once I got the D300 I gave it to my partner and she finds it easy to use as well. Benefit of the Pentax over the other entry level cameras is that the focussing is in the body, rather than the lens so your lenses will be cheaper and lighter than the competition, the K100D also has a dust removal sensor too that's a great bonus. It's not very well weather-proofed so be careful if you get caught out in the rain.