Pretty miserable, for the most part. The average Liberty Ship wasnt designed for crew comfort, it was made to transport goods and supplies from point A to point B. For the crew, it had a galley (kitchen), berthing(bunk rooms), heads(bathrooms) and a small r&r area. I remember reading a book by a British Merchant Mariner, he described how the galley(kitchen) was in the middle of the ship and the mess(dinning room) was in the rear of the ship, they would have to transport the food on the walkways exposed to the elements, sometimes a wave would hit and there goes dinner for the crew. The crew had to bring their own entertainment. You were there to do a job, steer the boat, man the guns, keep the ship running. here is a good website for more info on this http://www.usmm.org/men_ships.html

Now some merchant ships used in the war were nicer then the average Liberty ship. Some were "cruise ships" used to transport men, others were tramp steamers, used to transport men/supplies. Depending on the type of ship you might have more of a easy assignment or a harder assignment. But you need to remember that most of the ships were re fitted with defense weapons and added storage areas. O and the threat of Uboats, being adrift at sea in the life boat or worse without one.