The headline would be more persuasive if the article offered anything other than anecdotal evidence that Mint is picking up significant numbers of disgruntled ex-GNOME 3 & Unity users. But it doesn't.
I hand-plotted a few months' of data before deciding it wasn't necessary to go further: from August 2012 to October 2012, Wikimedia saw an increase of 1.1 billion page requests from Linux operating systems (a 10% growth for Linux in that time period); of those, Ubuntu gained 230 million page requests while Mint remained steady at 11 million page requests during that period.
Just to be clear, I would have liked the story that Ubuntu users were flocking to Mint, but that appears to be a fiction at this point.
I still run Ubuntu.
"The DistroWatch Page Hit Ranking statistics are a light-hearted way of measuring the popularity of Linux distributions and other free operating systems among the visitors of this website. They correlate neither to usage nor to quality and should not be used to measure the market share of distributions. They simply show the number of times a distribution page on DistroWatch.com was accessed each day, nothing more."