That HTML5 'thing' 'tis like a buggered up Superman logo, is this indicative of its performance?
Copying the Superman logo then buggering it up has to be a worry, it doesn't leave users with a great deal of confidence.
I've looked at most of the HTML5 drafts as they've become available and to me version 5 is a gross disappointment. It's strictures are sufficient that HTML5 ought to be called 'XHTML lite', and the 'enforced' use of CSS will ensure that HTML 4.1 will never die out. (I wonder what colour W3C jackboots are?)
HTML5 has been deliberately designed to suit the browser manufacturers more than ordinary normal users, so quick and dirty hand coding for simple jobs will future become a pain (a clear separation between XHTML and a simple and flexible HTML would have made sense, now we've a gooey messy compromise that will mostly annoy).
Moreover, HTML5 done nothing to reduce the maddening and ridiculous plethora of Web standards, in fact it's made matters worse. Tower of Babel eat your heart out!
HTML5 should have been a straight forward simple upgrade of 4.1, instead we've an over-bloated, inelegant, 'structured' monstrosity that could only be designed by a committee of anally-retentives.
Even Microsoft couldn't do worse. Perhaps the Microsoft non-standard HTML virus virulently mutated before it hit the W3C camp.