In January, Oculus shared a list of recommendations for a good VR experience as a PDF, and kept updating them since then: Oculus VR Best Practices Guide.
More recently, Tom Forsyth gave a talk at GDC 2014 where he gave some guidelines on what to do, what not to do, and what they haven’t figured yet about making VR experiences. The talk is available in the GDC Vault: Developing VR Experiences with the Oculus Rift.
Michael Abrash of Valve gave a talk about the near future of VR: What VR could, should and almost certainly will be within two years. Much of it deals with the notion of “presence”, the sensation of actually being in the virtual world, and what makes or breaks it.