No, I have a 60 Hz monitor. Yes, I can only see a maximum of 60 frames per second, but excess frames are simply dropped.
The advantage is increased responsiveness for most games. This is particularly true when your system can't quite keep up with 60 fps. In that case, I'll be running at ~55 fps instead of 30 fps (which is what happens when vsync is on). That's a huge improvement!
Essentially, you get framerates similar to vsync OFF, but with NO tearing artifacts.