"Freestyle" means dining where you want, when you want. My family and I cruised on Carnival two years ago and had assigned seating. The problem was that we had an assigned table at an assigned time. If for any reason you were late, you could not eat in the dining room; you had to go to the buffet and stand in lines waiting for food (this happened to us the last day of the cruise - not a good way to end a cruise). With freestyle you don't have to go and eat until you are ready. It also gives you an opportunity to eat in any of the main restaurants rather than just one. As for dress code, NCL does have formal evenings, but its usually confined to one dining room, so you can still have a normal sit-down meal elsewhere without dressing up.