Apparently short but very sweet.
This is a glowing review:
http://www.eurogamer.net/articles/2016-10-06-batman-arkham-vr-review
This is a glowing review:
http://www.eurogamer.net/articles/2016-10-06-batman-arkham-vr-review
I haven't completed it yet, but it definitely has a bunch of cool stuff. I think it should be fine to wait until it is $20 though.
And not having a big interest in this particular version of Batman, I do like something like Bound much more. But that is very much a matter of taste.
Finally finished the 'main' game... OMG this was so intense. I never imagined VR could be like this. I knew the game was immersive, but near the end I noticed my heart beating in my throat. I played it over several sessions though because I was warned on it being to short. In hindsight the game itself has the perfect length. Now for the extra challenges..