It's a great thing, Lin, and I've had mine for at least 15 years. Only problems with it - leaf motion will sometimes trigger it so best to not use it on windy days, and I can't use mine inside the fence perimeter or the cat comes in wet and very annoyed!
Oh, meant to add the 'range' on it also depends upon your water pressure, of course. I noticed mine sprayed one day in a very wimpy manner, and then realized that the rest of the sprinkling system was already running. Usually it's a brisk, noisy spray for about 3 seconds "Tschh, Tschh, Tschh". Very startling even for me! (yup, it's 'got' me a couple of times)