The most important feature: Apps.
Apps make FOS to FOS. They are the base of the increadible revolution FOS is. Here are only some of the great apps FOS includes.
Photos: The best way to manage your photos
Files: To always have everything organized
LibreOffice: To create impressing documents
Midori: To live the web the way it is meant to be lived
There are many other great apps included straight into FOS. Springseed to never forget something, Wine to always have your Windows software ready, Telegram to always be in touch with the people you care about, Mail to always have your mails ready and much more! Get FOS to discover it.