I tried them out at the VRLA Expo. Sorry to say, but not impressed. Dr. Huang, who built that prototype, pretty much said this won't be a product, and he barely had any funding. In his presentation, he mentioned the prototype was built with a few hundred dollars of stuff he bought on E-Bay.
He mentioned it reduces eye strain by allowing natural focusing, but I'd argue a lot of eye strain comes from focusing close. As long as HMD's have the focal point relatively far from you, I don't think eye strain is an issue. In the demo, he switched between conventional and lightfield rendering. While there was a difference, I could only tell when being compared side by side or right after another. I doubt it would be noticeable unless you were told. All this at 50x the processing power needed currently.
This might shine if you're simulating looking at things very close up. Not really something I've seen in any VR applications thus far.