What is it like working on a cruise ship?

Ive dont ships for 10 years.
I like it a lot, but just make sure she goes for a staff position and not a crew one.
Staff are the receptionists, pursers, photographers, casino staff, gift shop and spa staff, shore excursion staff.
Crew are the cabin stewards, waiters etc.

As a staff you usually have access to passenger areas, bars, restaurants, gym etc while you are off.
As a crew you dont.
Staff have better cabins, better onboard status.
It may not seem like much but when you are working 7 days a week for 6 to 9 months it is, believe me.

I was a receptionist with Carnival and later worked at the shops with 2 large concessions
and

I like harding better, pays more and its easier to get in.
Dont believe in those web sites that promise jobs on ships, its all BS. Do it yourself.
Its easy
Another plus of working for the shops is that you usually have port days off, since the shops dont open while on port in most cases.
Hardings runs the shops on some 50 ships and starboard on 90 or so.
Remember, bigger is not necessarily better, that goes for both the company as well as for the cruise line.
For me, the small the ship, the better to work.
Good luck