It's based on
sparse voxel octrees, a technique that is quite efficient in terms of computation requirements per screen resolution, and needs lower amount of data and storage than classic voxel engines.
Disadvantage is that some things that are fairly easy to do with polygons are considerably harder to do with SVO for the same level of quality or naturalness. Zooming in without getting blocky appearance, and mainly the problem of animation and deformation. But also lighting, shadows and other things.
Albeit all those issues can be solved or addressed to some extent, it needs a lot of development to be invested into it, and still it's questionable if it will ever be able to compete. Its inflexibility is a huge problem.
That, and those guys pushing it by way of claiming there's a kind of conspiracy in the industry against this universal remedy for all problems, doesn't add to the credibility.
On the other hand, I feel that that voice has the potential to disqualify any tech