Yeah, the full HTTP/2 support was a pleasant surprise! Wonder if Google's (and other prominent ones) web properties have switched over to HTTP/2 from SPDY yet.
Yes. According to Patrick McManus (owner of Gecko's networking stack), 9% of Firefox requests are already using HTTP/2 with the draft implementation enabled for Google (and now Twitter). With Google alone, HTTP/2 usage is already higher than SPDY.