The other thing I like about flip to mute is that it's an easier gesture to execute than toggling a switch or a two or three step mute on some other phones. I can never remember which way is off on the iPhone so I always flip the switch twice until it vibrates.

It's not a game-changing feature, but there are lots of little details like that on the S3 that make it feel like something Samsung really put a lot of thought into.