The K110D/K100D/K100D Super (in order of increasing feature set) is an excellent consumer DSLR - it serves me very well - and its most significant features, missing on, for instance, the D40 and 400D, are:
A metal chassis and tough resin casing (it weighs in the same as the D80) giving it a build quality to rival ANY consumer and prosumer DSLR up to the 40D
effective shake reduction (not K110D) (2-3 extra stops - you can hand-hold the camera for twice to four times as long an exposure, without getting a shaky picture)
a good kit lens (the Pentax 18-55mm kit lens isn't like Canon L glass but it's a head above the Canon and Nikon 18-55 kit lenses, particularly when stopped down to f/8, and better built too)
It takes the same lenses as the K10D, except the non-Super models can't autofocus the new Pentax SDM lenses (with the built-in AF motor). Not a great loss - the cheapest SDM lens is £550 and the benefits are questionable.
It's slightly smaller than the K10D, and a few things are always to be expected with a lower model - it takes a little longer to change settings and the continuous drive speed, as well as general camera stuff like picture saving, is a little slower. But for most casual togs it's more than adequate, and the money saved can be spent on lovely glass...
The sensor resolution is also lower of course, but with a 300mm lens (er... 70-300 zoom? 28-300 zoom? or a 300mm prime?) you won't need to crop photos much, and you'll be good for most enlargements you'll ever need to do.