Alas, this poor lens gets a bad wrap.
It was given to me a few years ago, by a friend who owned a handful of barely used Pentax legacy lenses. I made a few photographs with it and put it away for almost 2 years. So, I'm guilty of neglect. I came across it a few days ago while attempting to organize my gear, and decided to pop it on my K3.
It gets brutal marks for Bokeh and Sharpness, but I honestly can't confirm either of those findings. The real challenge is the lack of
Multi-Coating, you've gotta manage your highlights. Other than that, this lens is pretty damn good, IMO. Perfect center sharpness wide open, and I really like the Bokeh.
https://www.pentaxforums.com/lensreviews/Pentax-Takumar-28mm-F2.8-Bayonet-Lens.html