It's a fun toy for games (you will want to buy a bluetooth controller), great for VR video.
You will need an S6 or newer, preferably an S7 or newer.
There's a special Oculus store where you can buy or download for free games / experiences
https://www.oculus.com/experiences/gear-vr/
Game-wise PSVR is the next cheapest, especially if you already have a PS4 and is far far superior (proper games, proper head movement). Oculus Rift and HTC Vive both step up quality again. The gear can only process rotational head movement (fine for video, it's all that is possible), the others allow you to lean forward/back/left/right also, greatly increasing the effect in games.
There's a free video app "Samsung VR" that has loads of frequently updated VR video content, sometimes quite good - recently there was a VR prequel for the new series of 24: Legacy for example.
There's a free app called NextVR that broadcasts occasional NBA matches and other sporting events live in VR, I think they did Masters golf last year too. I think NBA league pass is needed for the NBA games.
There are VR porn companies that sell lots of VR porn to download.