alt Hacker NewsAtomic rollback is kinda big for servers.
If you manage enough diverse servers, then patching will break something critical fairly frequently. Back when I was a sysadmin, Windows updates would break some server every 2 months, and Redhat every 6 months.
Being able to just reboot the server back into a working state, and then fix it at a later time would have been nice.
It's also a big deal for desktops, especially when they're operated by people who ain't experts at troubleshooting software issues. Aeon's my go-to when setting up computers for non-technical folks specifically because I can have it auto-update fearlessly, knowing that the absolute worst case scenario is having to talk someone through booting into a known-good snapshot.