This lens gets mediocre reviews over on the Pentax Forums. I happen to like it. These first 3 test shots were all taken wide open. I'll add more at different focal lengths anon.
Not a scientific test, it was windy, camera wasn't on a tripod, distance would have varied slightly but I did this just for fun. I'll probably add more at a later date. I'll leave you to make of this what you will.