A system that boots up in seconds and the overall computer runs smooth. Setup requirement is minimal. A user only has to flip open the Chromebook and login into a Google account.
Maintenance is also hassle-free unlike other operating systems like Windows. Google also updates the OS regularly and automatically. Chrome OS also has a build-in anti-virus protection. There is also no need for regular updating of several apps unlike in OS X because Chrome OS apps are stored in a cloud.