Well I sold my Nikon set, a D40 with accessories and 3 lenses, and I ordered a Pentax K-X
I look forward to having extra stops on account of the cool high ISO availability
The main reason I decided to sell all my stuff and switch over to Pentax 100% was their dedication to legacy glass. I really enjoy using the old lenses in addition to the new stuff, and everything in between.
My D40 had the metering of manual lenses intentionally disabled (even though they actually fit) - it was really irritating because sometimes I just like to use a 135/2.8 or a zoom with constant 3.5 aperture. It also lacked the in-body motor to use AF lenses, what a drag for a shooter on a budget that needs something outside of the 3 affordable kit lenses.
Besides Pentax's dedication to preserving and using the legacy glass, I think they give the most to their users. It seems that each entry level Pentax body is crammed full of nearly every feature Pentax cameras have to offer - and not just fluff, useful things like super high ISO and in-body HDR. Their entry level cameras don't feel as if they were intentionally crippled like Nikon's does.
I also like that they make solid equipment, for example I think Canon's "low end" is much too low, I've seen Canon entry level gear that was easily broken. Pentax's gear (that I've handled so far) seems nice and tight, good and solid.
I also feel that Pentax is innovative, they seem to be trying all kinds of different things rather than just sticking to a formula. My K-X is as white as snow, that's a unique offering
And the array of new prime lenses available is really cool.
OK, I'm a 100% Pentax user now
Cheers,
Craig