(off the job) ship life is the same no matter where you work, but the advantage to working in shops is that they are always closed in ports - so you get to see the ports of call.
The only disadvantage is that you will have long days working when at sea - often boring late hours - depending on the ship and the shop.
Most likely you share a cabin with another shoppie - the good thing is that you probably won't have a lot of "boss" issues since you work for a concession.
The main thing about ship life is this - as long as you stay under the radar and show up for your job you shouldn't ever have any problems.
I am the editor, but I also speculate, ask questions and play devil's advocate. I reserve the right to change my mind.