We took them and had trouble on board the ship. There is a lot of metal in that ship, and metal interferes with radio waves. We have motorola 2 mile ones. They worked great on CC, great when you were stretched across one deck (like Scoops to the adult pool) and pretty well as long as you were within 1-2 decks. They didn't work from the movie theater on Deck 5 to the Goofy pool on Deck 9 (DH tried to tell me he was sending DS up cause he was bored in the movie, and I never got the call, so DH came up with him).
If you already have them, bring them. But I wouldn't buy a set just for the cruise, unless you're willing to spend a pretty fair amount for very good ones.