I have played Valkyrie and it was awesome. I also played the cheaper gun whatever one it is called for the Samsung phones. They both work really well. Much better than i expected. However i tried the cardboard thing for phones and it was terrible. You really need good head tracking to work. Phone gyros don’t cut it.
Even if they get popular because of other applications, it makes them common. Also AR requires quite different features than VR. I really like the idea of AR but it always going to be transparent, until we get 3rd generation retina implants!