Since I have had this lens it has been on my Pentax K20D all the time and has seen a lot of use photographing flowers and insect life as well as some portraits and a couple of landscape shots.
I have found it to be extremely sharp and give a beautiful blurred backgroung to macro shots and portraits.
Mounted on a solid tripod with a remote release or mirror lock up the results are amazing.
I have nothing but praise for this lens