I haven’t used it because most games don’t work or have as good of performance. Benefits in short term will be things like in-tree kernel module, better working relationship and bug fixes with open projects like KDE/Gnome and maybe things like Gamescope or VR.
Now, if you want. There will probably always be tradeoffs between the two drivers so I doubt this will ever match Nvidia’s across the board, just have to pick your poisons.
It’s under the shield on the left of the address bar, better protection against tracking enables this and a bunch of other features. Also on by default in private mode.