Well, maybe I'm one of the few who had a good experience with IF. My parents have it for their beagle. They live in a very wooded area, so a real fence wasn't really an option. They also live in a very rural area however with very little traffic, so if she did break through, which she doesn't, its unlikely she'd get hit by a car. She actually doesn't need to have it turned on anymore. She knows where the boundaries are and doesn't even attempt to cross them. Not to chase a squirrel, a rabbit, or anything. But she's not out there by herself for very long. As far as other dogs coming in, yup, that happens. Chester, the neighbor dog comes to visit quite often (he was a stray that a neighbor took in and fixed who apparently misses his roaming days). They haven't had any problems with their IF, but I know a lot of people who have had problems. It's definitely a hit and miss deal. My grandmother has one for her rottweiler, and she also hasn't had any problems with it. For some dogs it works, and for others it doesn't, but the tricky part is, you won't know until you spend some money putting it in. You may just end up with a useless underground wire surrounding your house. But that is my experience with IF, I neither endorse nor denounce it. It all depends on the dog.