Perhaps the thing I like most about the Pentax is the compete lack of surprises - everything works logically. I have the open aperture live view focusing that I used to have on the Canon and really really missed on both the Nikon D800e and Sony A7r. You may thing this is a small thing, but if every single exposure you have to change the aperture to wide open, focus, then stop down again, it really is a pain - and if you forget to stop down again - disaster. And if you are in manual exposure - forget it because the screen gets too bright and you have to change the exposure too - so nice to be back the right way. And I always have the option to preview stopped down but if you aren`t using especially fast lenses, focus shift is not a big issue.
Turns out I like the weight and size of the body - it just feels so solid, and I don`t have the sense with long lenses that they need separate support - which makes changing lenses that much easier.
I find I don`t really need the 150 mm. lens - too close to my 120 to be worth the trouble, and I`m replacing the old 200 with the better 200 FA so I`ll likely carry the 25, 35, 75, 120, 200 and ?300.
I need to do more testing on the 300 both to see if shutter shake is an issue (I don't think so) and resolution - it's sharp in the centre, not sure about the corners yet.
I really like that the tilting lcd screen moves away from the body when you look down on it, not partially hidden by the viewfinder, especially if looking at it from an odd angle, like the camera aiming downwards but higher than I am.
I like that the lenses and lens caps screw on the right way unlike Nikon. The viewfinder is great and with glasses easy to use including the data display. It's easy to both use and see exposure compensation, and focus comfirmation works great, with the focus point glowing red in the viewfinder, unlike Nikon that had that little green circle at the bottom of the screen.
ISO has a dedicated button so really easy to use.
These may seem little things but they sure do make shooting more pleasurable and working the camera less distracting.