Baby Sign Language – Good or Bad Experiences?

My first son picked up all the signs I taught him. I did just the basics though, like Thank you, more, please, drink. He’s 3 years old & still does the sign for please while saying it. My second son only picked up on more. My third little guy is just getting to where I start (7 months) showing them the signs. I don’t have anything negative things to say about doing baby signs which by the way is a book Baby Signs.