The publication of the candidate is on track with W3C's original roadmap, which placed the candidate releases in Q4 2012, along with information about the penetration of HTML 5 features in web browsers, stability of each feature, interoperability of components, as well as an outline of potential at-risk features. The final spec is not expected to be released until Q4 2014.
Web browsers are not adopting the same features at the same pace, but show preference to their respective product strategy, which leaves developers at a state where they can only leverage a limited feature set that all browsers support at the core. It is not unreasonable to expect that it will take at least two more years until all major browsers will support all recommended HTML 5 features.
According to caniuse.com, IE10 currently supports 74 percent of the HTML 5 working draft features, Firefox 76 percent, Chrome 94 percent, Safari 77 percent, and Opera 77 percent.