I've had my K-7 for nearly week now; have had a K100D in the past and still have a K20D.
I've not had much time to get out and an do anything serious; so just had a good play at home and a good read of the manual while playing with menus...

Usability...
1. It does feel different - not bad - just different to the K20D (K-7 is smaller)
2. The extra controls are great - just takes a little getting used to
3. The new Menu is better - the Info button is part of that system so get used to it
4. You really need to take a good hour or more to understand the new usability
5. The new viewfinder and liveview are great - horizon indicator! (3" 921k px)
6. AF is MUCH faster
7. ISO button is a good move
8. Metering seems good
9. Nothing missing from the K20D - just different
10. The push button needed to turn the mode dial was anoying at first but you cant accidentally switch modes either
11. Had to upgrade the firmware to 1.01 (shipped with 1.00)

Movies...
1. Capture works well - what can I say
2. The inbuilt audio pickup sux - external mike is require if you are serious

Images... (from the little I have done seriously)
1. Have two images entered in comps
2. Sensor while faster (frame rate) produces what the K20D did (and I'm happy with that)
3. The new HDR is interesting - JPEG only - but does well - must use tripod!
4. The new shadow compensation seems to work well
5. ISO 6400 is ok if you use the NR at medium or higher
6. ISO 1600 is better than I expected
7. The extended dynamic range is better than the K20D
8. Shake reduction is at least as good as the K20D - cant really test but I'm guessing maybe 1/2 stop better
9. I could not get the 'green line' syndrome a few early units had (as reported elsewhere and limited to a couple of batch numbers) - GOOD

I think I have a lot of playing to do
I'll post images over the next few weeks as I learn how to use it.