The flagship ergonomics and sense of quality build since the K-7 just click with me to a point where the camera feels like an extension of myself, the moron behind the camera.
I just like to touch and operate these cameras. Have never experienced anything quite like it before. If Pentax ceased to exist and I decided to change systems, I'd probably look at Nikon for anything remotely close.
I do agree to some extent with those holding that different is not necessarily better, and that some of all this may just come down to taste or personal preference, but then after twelve years of happy use I'm strongly prejudiced towards Pentax, I guess.
I also like the way Pentax design favours ergonomic soundness over retro styling as an end in itself.