The K-01 has received sporadic use as I recover slowly from a virus, and take care of my unwell spouse. What it has revealed is both amazing and frustrating, and it will teach me what is valuable in my style and what is just old habits. That's a good thing.
The first obvious item is the view. I really like viewfinders, love the K-5 real-life view and tolerate the G1's 1st-generation electronic VF. And now the K-01, which is live view or nothing. I can manage any of them, though my varifocal reading glasses do make the K-01 positioning quite important. Virtual views have their place, as they show exposure and white balance that optical finders cannot match. In any case, while I prefer the K-5 on this I can manage (for a week at least!) with the alternatives.
As to focus, and full-time contrast AF? Again amazing and frustrating - focus is more leisurely than I like, but it locked precisely on a shot in very low light that I'd avoid with the K-5. I don't calculate EV numbers but a shot of my bookshelf was 1/13, f/3.2, iso5000. Motion blur was erased by SR and iso did the rest, and the image looks like all lights were on in the room. Amazing. Add to this the focus-peaking ability, which dramatically speeds my manual-focus times - and once again I can only say the K-01 system is not bad, just different. *NOTE* the v1.02 firmware has made a big difference in focus speed and accuracy. Still different, and now better... but the K-05 has also been updated to v1.14 and presumably its CDAF is faster too.
And the images look just great, maybe a bit punchier at first glance than my K-5. I've adjusted my custom-image settings on that camera though, so no comparison is fair at this point. Many have commented that their K-01 images look 'better' than K-5 images, which can be attributed to more precise focusing, a year-newer 16Mpix sensor, the Prime-M support chip, or firmware tweaks to the processing. Maybe even the low-pass 'AA' filter, which seems to be weak and thereby allow more detail. In any case jpeg images are definitely not a step down.
OK let's talk about the K-01 ergonomics. I haven't played enough in a week, and I haven't read much of the manual, so I'm at the grumpy part of the learning curve. I am used to using ±EV by holding the button and turning the dial, and my hands cannot do this on the K-01 - but then I learned to press ± release and then dial compensation... and that works fine, once again "just different". My grip is awkward but pretty secure on the body, but a few fingers have not found their happy place yet. I see that many users shoot with their thumb on the shutter, which I have not tried yet. I also have not decided which assignments will serve best for the red and green buttons, so as I learn the camera will begin to fit me better.
I really like the white with black knobs, whether 'stormtrooper' or 'panda' nickname is used.. some are even going with 'pandatrooper' FCOL! It's a cute white brick to me, maybe CWB will serve. I'd like a snow themed nickname, and thinking snow brought me to the abominable snowman. Given the harsh reviews this camera has received, the abominable Pentax came to me. Maybe that will stick, maybe not... 'ghost cam' fits just as well, and its talent was invisible to most reviewer/art critics.
And least but not last, video. I hear it's great, and I expect to make use of it - but I haven't yet, so no comments on SR, jello in motion or other features/failings. More to come on that. That fact that the K-01 can do normal video with compression, 50/60 fps for slo-mo and interval-timed movies has my attention, but I have to see it in action to see if it has a place in my way of doing things.
Changing to 1:1, 16:9 and other ratios is something I often do in playback mode on the K-5, and it's nice to have those settings in advance for framing. Image quality is great, as noted above, and nearly all the K-5 options are available (at least the ones that I've used on that body). The K-01 sits closer to me due to lack of a viewfinder cup and the strap-attachment setup; with a small prime it's an easy under-coat camera. Focus peaking is quite excellent and will be used with AF lenses not just MF, and really it renders AF speed irrelevant in most instances! I really like the Li-90 battery compatibility! More likes will come as I try more, e.g. I expect to make good use of the interval-timer movie mode at some point.
Not So Hot
AF speed is still a challenge, and looking at the big screen all the time is not my preferred option. AF sound seems louder, no surprise with the hollow space in the camera. As noted above though, peaking lets me focus quickly and get the exact spot I want in focus, so this is more a whine than a real complaint. I can see how some with less patience would go mad over the rubber-door attachment but it hasn't gotten to me yet. I do wish the rubber wrap had extended to a spot for my thumb, but it isn't a large annoyance. Um, really that's it as of now. More likes and dislikes will come, I'm sure.