I have the K850i, there are a couple of things which irritate me a little.
1 - It seems a bit slow, especially with the touch screen things at the bottom, whatever the buttons are called. Seems to take a while to get into menus and stuff.
2 - When taking pictures, if you have your finger even slightly on the surface where the lens is, then the picture is very dark. And I mean, even if your finger is slightly on the edge of the face, then the picture will be dark.
Other than that, the camera seems good, the media album once you get used to it, is nice to use, and the functionality is much the same as all the other Sony's, which suits me.
Lots of reported technical faults though.
I thought I was gonna have to send mine back after 2 hours, as the auto lens cover wouldn't come off the camera, seems ok now though.