Mine is almost always off, unless I need to call someone, or call home. I don't give the number to many people for that reason - trouble is if I'm working (performing, storytelling, teaching) I definitely don't want to be called and wouldn't answer anyway. But I use it to call home when working away (far easier than trying to find another phone), to check my email when away from the computer (I can read but haven't sorted out sending yet, which is fine because I can check if there's anything urgent), and to call our home answerphone and check messages. If we're on separate errands we can check in with each other, and when we were still living 120 miles apart it was a wonderful thing to send a brief loving text. I originally bought one so that I could call for help when my unreliable car had let me down - these days I don't need it for that too much.   
I have used it as an alarm clock (I prefer the real thing but when travelling light it's handy) - my husband always uses his as an alarm, as he reckons he can change the sound often enough that he doesn't get used to it and sleep through).
And the camera has been useful if I've forgotten to take mine, as well as for spur of the moment snaps from the car (when I'm a passenger).
In short - wouldn't really want to be without it, even if it never actually rings.

Anne