With a few notable exceptions, it is very, very good, but not true gourmet dining. The food ranges from nearly gourmet food on a few of the upscale ships to consistently good and even great on occasion on other lines. On the larger ships, they get a thousand or so people in and out of the dining room, only to repeat the trick at the late seating yet again. During this time, bring your camera and behold fantastic ice carvings and food extravaganzas. Except on the luxury lines the idea of dressing for dinner has been toned down a bit.
Men can bring their own tux or on many ships, rent one on board for the formal nights.
Women wear their finery and beautiful gowns. On the other hand, on formal nights, men can also choose to wear a dark suit and women, a nicer dress. Our experience has been that people enjoy getting dressed up a bit. Cruise lines typically vary the suggested dress, so you will have some evenings when the recommended attire is casual. The truth is, this is your vacation.