It's a perennial problem that authors of free software get little feedback from users. Here's an idea: add "I like this program" and "I don't like this program" buttons to Help/About dialogs. They would send some kind of anonymous signal to the author, probably by making an HTTP call to some server somewhere.
This is not a "call home" functionality, which is questionable in many ways. It's completely opt-in, and it's pretty clear to the user what's going on.