"Regarding proactive negotiation in HTTP/2, I'll note that Waka strips all negotiation fields. I find the entire feature revolting, from every architectural perspective, and would take the opportunity of 2.x to remove it entirely."
Roy Fielding
http://lists.w3.org/Archives/Public/ietf-http-wg/2013JanMar/...
What I really don't like is they don't accept my accept headers, and I have to change the extension on the end. Going to /.json feels like ilk to me.