This site now uses the new version of WordPress, version 3.5. Many changes, but mainly in the back-end, the admin site. Also new is the default theme, Twenty Twelve, which has a responsive layout, i.e. the layout will be adapted depending on the screen size, so it will work as well on a smartphone.
Before, I used the Roots theme, a.o. because it has a responsive layout. The previous default theme, Twenty Eleven, was not responsive, en therefore less suitable for mobile phones.