Some photo samples are posted in a thread at the Chinese Xitek Pentax Forum, here it is:-
http://forum.xitek.com/showthread.php?threadid=790281
(in Simplified Chinese)
The photos were taken at the Photokina exhibition hall indoor, you can find downsized images taken at 18mm f/5 and f/5.6, 31mm at f/5, 68mm at f/4.5, 78mm at f/5.6 and 3 other samples 135mm at f/5.6 (here for a middle-distance scene, here for testing the bokeh and here for verifying the skin tone).
After viewing, I do have some good impressions about the IQ of this lens. There is no obvious CA seen, the photos are considered sharp with good contrast (despite they are downsized), bokeh is nice and colour response is okay (the actual colour accuracy/tendency cannot be judged exactly for those indoor environments with artificial lightings anyway).
The barrel distortion at 18mm is a bit dominant but it would be of no surprise for such long-range zoom in 7.5X, nevertheless.