Not a bad piece of software – actually, it's pretty good. The only reason other users are slamming it is no doubt the fault of its nature as a Flatpak. In-short: If you don't let Letterpress have access to more of your computer (or simpler: total access to "all system files") with something like Flatseal: it *will* complain about "incompatible file formats" and throw an error, which is frustratingly common in some Flatpaks. *But* once you fix that, you unlock a pretty nifty, if niche piece of software, with a decent GUI. I'd be able to recommend it more comfortably if it either had access to everything it needed to by default, or was at least more transparent than throwing a "file incompatibility" error out after a PNG.

The software runs but won't accept any image format I throw at it.