The Sparks family uses Find Friends all the time. With my kids off at events, jobs, and school, we often check up on each other. I like to think of it as a nerdy version of the Weasley family clock. We're not creepy. Really.
The one piece of this I don't understand though is why Apple hasn't found a way to put Find Friends on the Mac. (It's also not a part of iCloud.com.) I would guess this is an issue of engineering resources but now that we have Maps on the Mac, I hope Find Friends is not far behind.