Tight with the Boss?

So you're getting pretty close with your boss. Friendly. You talk quite a bit, and mostly about work. You are starting to discuss other coworkers, including one or two you don't particularly care for. Your boss is pretty open about his/her feelings too. It feels good to get things out in the open, doesn't it?

But have you crossed a line? Should you and your boss really be discussing work issues like this? Who is taking the bigger risk, you or your boss?