Today’s top porn VR videos are recorded in 8K, but if you play them from an old HMD the experience will be subpar. How realistic and immersive precisely depends largely on the viewer you use and the video source. It may remind you of the 3D movies that became popular a few years ago, but much more advanced, immersive and realistic. The main one is a complete sense of presence, volume and depth. The advantages of VR porn are pretty obvious.
