Quick and easy for small enclosed ares as has been said. Don't use it anywhere where strength or moisture resistance is a concern. I have used it limiter fly in my project due to convenience. It is not cheaper than pour foam, btw. No reason to use it except convenience in very small areas that are well protected.
A good spot is around the rub rail area. Sometimes it gets to banged up you don't have much to work with. Spray some foam and let it do it's thing. Then you can cut it with a razor to give you something to glass against.