It’s an interesting approach: instead of going “full responsive”, they’ve opted for a responsive mobile site (with some server-side detection help) for smartphones and tablets up to seven inches. It looks great on a phone, it’s a bit more problematic on tablets. For one, detecting the difference between an iPad mini vs. iPad (maxi?) appears to be buggy at best. The server-side detection they use doesn’t seem to do a very good job when sharing links — a link emailed from the mobile site opened on a desktop browser will still show the mobile layout (and vice-versa), for instance. That said, it’s a well designed compromise that certainly addresses some challenges media sites have with responsive designs, namely dealing with ads.