When I first used Calibre I thought it was a disorganised mess trying to cram too many features in one app.

Over time I learned to appreciate the vision: it’s not the stereotypical modern streamlined app, it’s the cockpit of a spaceship. It’s AutoCAD for ebooks. I really enjoy that application now, I haven’t even scratched the surface of its featureset.

I heard the author gets very defensive of his design choices: good, I wish we had more opinionated app developers in FOSS.