It's a good way to force yourself to disconnect from work email and social media for a bit, but still be reachable. Leave the phone at home, and just wear the watch. You can still take a call or reply to a text from the wife in a pinch, but doing email or checking twitter/Facebook/hacker news isn't an option.

I try and do this now when I go out with the kids to the park so I'm not tempted to be buried in my phone.