There's pages and pages about it on the web.
The Polystar is conjecturally 'polyester'.
It is a movie print film and has no AH backing so use it with a camera that doesn't have a highly polished pressure plate.*
It seems to be the old Pan F coating, not the plus.
It is very popular with the Caffenol putsch. No problem pushing to 100 and in Diafine even more.
The sprocket holes are just perfect in spacing.
You have to get to live with the lack of edge markings and the bigger reel. What more do you want for that money?
Look at the Flickr site and see what can be done with it.
If you haven't tried it, don't knock it. Great for the frugal.
*And to kill the flare, should you have a problem, try covering the pressure plate with 120 backing paper. An instant cure.