I’ve been involved with Linux for a long time, and Flatpak almost seems too good to be true:
Just install any app on any distro, isolated from the base system and with granular rights management. I’ve just set up my first flatpak-centric system and didn’t notice any issues with it at all, apart from a 1-second waiting time before an app is launched.
What’s your long-term experience?
Notice any annoying bugs or instabilities? Do apps crash a lot? Disappear from Flathub or are unmaintained? Do you often have issues with apps that don’t integrate well with your native system? Are important apps missing?
I prefer them. There’s trade-offs (like disk usage and occasional theme issues) but it’s worth it to me for the sandboxing and ability to easily run a newer version of an application than your distro has packaged up in their repos. It’s better for developers since they don’t have to support deb, rpm, etc. etc. And long term, it’ll allow immutable systems to become the default and that’ll be good for security and stability.
Between Snap, Flatpak, and AppImage, I default to Flatpak. It seems like the best supported even if they all have their strengths and weaknesses. AppImage is great for old versions of software you don’t want updated/integrated into menus. Snaps are basically the same and I happily use them if there’s no Flatpak but it’s so tied to Ubuntu/Canonical that some people have opinions about using it. I don’t know of any developer stubbornly refusing to support Flatpak on ideological grounds.