Not much was shown, but we now know that it's a murder mystery developed by Rocksteady Studios. It focuses on Batman's detective skills and is exclusive to PlayStation VR.
Principal designer Bill Green wrote a post for the PlayStation Blog, in which he revealed that you'll be able to explore locations like the Batcave and Wayne Manor--the latter is a first for the Arkham series. You'll be able to stand in Bruce Wayne's home, then descend into the Batcave to don the cape and cowl.
With virtual reality's constraints, Rocksteady has put a greater focus on Batman's detective skills and found "new ways to use them." Batman: Arkham VR will feature a "highly focused, very personal story entirely in first-person." Green describes it as "a murder mystery in the style of the classic Batman comic books, but with a strong dose of the dark psychology that the Arkham games are well known for."