There’s a nice write-up in the MariaDB knowledgebase with particulars. In short, the 5.2 series of MariaDB and some of the unique features of the project have made a migration easy and valuable.
It’s nice to hear such stories. Both because we like interesting sites and projects, as well as our natural interest in larger scale or larger visibility deployments. Got a story to share? Please create a KB entry, or e-mail the community team.