There is one thing GeForce Experience does that's useful, and it's the reason I have an nVidia card and use it.
Game streaming to nVidia Shield handheld devices. I can tether my Shield Portable to my phone's hotspot and play my PC games wherever I've got a good LTE signal.
I don't use it to raid in MMOs - not that it wouldn't work, it's just a bit too finicky for me to trust. I don't want the raid to wipe because I got a phone call and my hotspot dropped.
But I play all sorts of single player games with it, and solo/level/quest in MMOs. (Just be sure you're using it on an unmetered connection. Constant 720p video streaming adds up.)