Is it a good idea to teach your child (who is just learning to talk) sign language?

My sister in law teaches my nephew (who just turned 1) sign language. He has no hearing problems whatsoever — she just taught him sign language so he can communicate since he’s too young to talk a lot. (he’s been “signing” since he was 10-11 months). He knows, “bottle”, “hungry”, “milk”, “feed me”, “all done”, […]