I lived next to two JW families (I still live next to one of them), and I got/get along well with them and, generally speaking, they were courteous.
My problem with them is not that but is the same problem that I have with many fundamentalists, namely that they take the "my way or the highway" approach, which is both condescending and insulting. In Judaism, such an approach is not allowed because it stands the chance of ripping a person away from their faith and leaving them with nothing.
Any religion or denomination that's based on a certainty of being correct is simply being foolish.