Its basically a second class medical but most controllers don't get a medical certificate like pilots do unless they ask for it. I do of course because why not let the FAA pick up the tab. Me being only 29 I'm only required to get my medical done I think every 2 years. So its obviously different because in that case I would run into 3rd class privleges.
There's a couple of other minor requirements over the regular Class 2 for controllers. And when we turn 40 you have to get your physical every year, rather than every 2. But like Lear said, its basically a class 2.