The latency between the physical movement of a users head and updated photons from a head mounted display reaching their eyes is one of the most critical factors in providing a high quality experience. Human sensory systems can detect very small relative delays in parts of the visual or, especially, audio fields, but when absolute delays are below approximately 20 milliseconds they are generally imperceptible.
According to the article
[...]the latest GameFace SDK significantly reduces latency to a point that it is easily comparable to the DK1. The company plans to benchmnark their latency soon to get a quantitative latency figure.
Notice that is DK1 latency, not DK2. DK1's latency was notoriously bad and made many people nauseous. So, while I'm happy to see competition in this space, as far as GameFace is concerned, there is not a lot to see here yet.