As anyone who has studied Virtual Reality will be aware the selling of the illusion of the user actually being in the location is paramount. This so called "place illusion" convinces the brain that what it is seeing and hearing is "real", so the key to strengthening and maintaining this effect is to maintain the the sound and vision as the viewer looks around and navigates in the virtual environment.
Now VR film is already a compromise, users cannot (at time of writing) navigate around a pre-filmed environment so the best we can hope for is that the photorealistic rendering which the user views is convincing enough. When this is presented stereoscopically, which should enhance the immersive effective, we would hope this can deliver the optimal place illusion for the user.
So this is where VR180 just doesn't cut the mustard - as soon as you've turned your head a few degrees you have the end of the image - the magic is gone and with this the place illusion is immediately broken. So while it is true that, as with any film, there will be a focal point which will often be within the 180 degree front view of the camera, what is the point of shooting this as a pseudo-VR experience?
Based on my experience of the market, and once clients are made aware of the important psychological effects of the place illusion, I've never had a client then ask for a "half VR" experience. Of course the reality is for the producer VR180 is simply easier to produce. VR180 can be produced without the challenge of stitching and actual production shooting and editing is not dissimilar to what a "normal" filmmaker would have been used to. So in theory it can be produced more cost effectively, but at the cost of halving the virtual impact. If it's simply for the stereoscopic effect it may even be that a more traditional 3D film would work better, without the limitations that a VR180 camera introduces - his could be viewed on a headset in a Virtual Cinema and deliver similar results.
If you're going to produce VR content I urge you to go for the best possible option. Go for the big picture. Go VR360.
Andrew Murchie is a creative technology consultant based in Edinburgh, Scotland specialising in virtual reality films & 3D. Over the last 5+ years he has produced Virtual Reality films & experiences for clients including NHS, Kimberly-Clark, The UK Agriculture and Horticulture Development Board, Highland Spring, Seafood in Scotland, Pict Offshore and Tennent Caledonian Breweries.