An display for every task
Two panels the size of a postage stamp carry more pixels each than a 4K television. The practical consequence is not the number: it is that text renders as text at arm's length, so a document is readable rather than merely present.
Input without hardware
Look at a control and pinch. There is no wand to lose and no glove to charge, and the gesture is small enough to use with your hands in your lap rather than held in front of you.
Sound that stays put
Audio is placed in the room rather than in your ears. A window you moved to the left still sounds as though it is to your left, which is what stops a long session becoming tiring.
Environments on demand
Replace the room with a landscape when you need to concentrate, and dial it back when somebody walks in. The dial is continuous rather than a switch.
Privacy at the sensor
Where you looked is computed on the device and never handed to an application. An app learns that you pressed a control, not that you considered three others first.
Passthrough that convinces
Cameras rebuild the room with low enough latency that reaching for a cup is not a calculation. Below about twenty milliseconds the hand stops hesitating.