Id say that there are a bit more cons right now then pros, here's why:

• The entire spec is still somewhat of a draft and can be changed at any time.
• Pretty much there's very little within the spec that is supported throughout all browsers.
• And QA tools still need to be tweaked a bit more becuase they end up lagging regularly.

But of course, to each their own. HTML5 is till an incredible technology that can do wonderful things.