Having tried it first hand, I at least am very excited. To me it's night and day different from a movie file on a fly through of your model or rendered stills.
Now, that said, how much value is there in that? How many genuine "Ah ha!" moments will you have where I client sees something that changes the design requests? I don't know.
We are still in the sweet spot of the new VR boom. The novelty factor is, well significant. When one firm fires up a power point presentation and another hands a group of people VR viewers to walk/look around their proposed building? Well it's going to be a memorable experience regardless of who had the better design.
How much additional work is that compared to the other guy? I don't know yet. My impression thus far is not a ton more.
As for using it internally, it will be a huge help for review IF we model things out to a high level of completeness. Right now we are still straddling the line of drafting in 3D and drafting in 2D. Our end "product" is a set of documents (blueprints) of floor plans, elevations, sections and details. In many cases it's more efficient to just draw them in 2D rather than model your whole building in 3D and extract a 2D view from it. That is changing... slowly.
In order to leverage the 3D end of things particularly VR, you need to be more aggressive in a complete model. That means we are modeling more than we need for our drawing package that goes to the contractor for construction. The industry line will talk up Building System Management and Building Information Management, but the reality of it, at least for us, has been light on those aspects of working in 3D.
Our design team, which hands off rough concepts to our construction document team however, works almost exclusively in 3D today. They create the marketing and graphics used to communicate with the client to settle on a final design. This is where I see the most benefit. Both with the client and for use internally. To your point however, internally most of us have a decent grasp of spaces and by looking at a plan and sections separately we rarely are surprised of the reality when experienced in person. So that may depreciate the value to us.
I haven't yet experienced that thunderbolt of, "Holy smokes! That is amazing and I couldn't do this without VR before!" But we'll see. A lot of people are excited about it and talking it up without clearly identifying what that may be. To those who can't look at flat drawings and see the 3D object/space/building in their mind? It will be huge.