You're on vacation, why do you want a phone?
If there's an emergency at home, you can be reached 24/7 in your cabin via the ships phone, and there is voicemail on your phone.
I wouldn't want to take my cell phone anyway, it's an analog bag phone I got in 1990. My daughter says it isn't a "real" cell phone. Funny, unlike her friends .6 watt digital phones, I don't get dropped calls, and I get service almost everywhere.
Disadvantage, or ADVANTAGE is, I don't take it out of the car. That's fine, if you can't reach me in the car or at home, I'll get your message soon enough anyway. And sometimes, I want to be UNREACHABLE.