I had one but it really didn't stop my dog. He would gladly take a little jolt if it meant he could chase the squirrels.

I was never happy that other dogs and people could come into my yard at will. I feel MUCH more secure with a real, old fashioned fence. I sorta went overboard and put up a six foot, treated board fence. It's been up 12 years without failing anywhere. My neighbors have thanked me for it, too.