I finally broke down and purchased the KP (the sale price was too good to pass up). I normally don't write about a camera, but feel compelled to do so this time. A lot has been said about the KP, plenty of it negative, which is a lot of the reasons I delayed as long as I did in buying one.
A bit of background: I've shot with the K10D (ist DL as backup), K20D, K5, K3 and K-1. All of the aforementioned cameras were used at some point and time for paid work, I did a lot of portraiture, both at the beach and for schools. Later, I started doing weddings, my most recent using the K-1, K3 and K5. Also of relevance, I have large hands, wearing XXL gloves.
Size: The KP is small, there's no question to it. But having used, and still using film cameras daily, I find the size quite similar. I've never had an issue holding onto my Program Plus, or LX, and I don't see the KP as being much different. The first lens I used with the KP was my DA 17-70, followed by the DA* 50-135. Both of these lenses are rather large, especially compared to the Limited line. Maybe it's my technique from years of film cameras, but I didn't find an issue holding the camera, even with the medium grip, which I have found to be my favorite.
Auto Focus The auto focus on this camera is far and above any other Pentax camera I've used, and I was quite happy with the K3 and more so with the K-1. The DA17-70 has become a new lens, quick, accurate and never hunting for focus. The DA*50-135, I'll have to reserve judgement on, my copy is a little sticky and I have to work the focus manually back and forth a few times before it starts to work, although after that it does focus faster than it has on other cameras.
The layout of this camera is really a thing of beauty. My thumb rests on the back button for focusing, and for the first time, back button focus is completely natural to me. I originally had a few concerns about not having a top LCD, but quickly realized I have no need for it with the KP. All of the dials and buttons are easy to access and in places which make sense.
As far as two card slots are concerned, to each their own when deciding how important that is. I shot for many years with only one card slot in a camera, and never gave it a second thought, so it was never a deal breaker for me.
As with my other cameras, I will buy a battery grip, which I find useful when I'm shooting portraits, but most likely, I'll only use it for that purpose or when I decide to use the KP for a paid shoot.
The flip screen is nice, although I would have preferred a set-up like the K-1. But I understand that would have likely made the camera larger/thicker.
Bottom line is this; The KP has received a lot of unwarranted negative comments, which I wish, I for one had ignored. If you're on the fence, this is one great aps-c camera.