We went on a two night Cunard from Southampton to Hamburg as an experiment. I didn't think cruising was for us but wanted to try it. We live in Hampshire so it was very convenient. The initial cost was £250 all in so it was very cheap. Once on board the drinks were a reasonable price on the menu. However they added 15%. service. If we have bought the drinks package it would have been £85 each per day. They also added £15 per day service charge for the rest of the crew. If we had wanted the internet this was £40 per day - I can't remember if that was per person or per cabin.
Once on board it became clear you were just two of 3,000 plus customers. The food was pretty good but if I tell you our table number in the restaurant was 439 and we had to queue to get in this gives you an idea of the scale of things. We were basically eating good quality ready meals. Load of entertainment which was of a high standard.
The cabin - described as a 'stateroom' was budget hotel standard and tiny. The bathroom was claustrophobic with the same type of toilet you get on trains.
However going back to the point of whether you invest the regulars clearly love the experience. There was a booking office on the ship where you could reserve future places and this always had a queue.
Not for us but if you like it fair enough. The additional, partly hidden, extras bump up the cost significantly. Too be honest it was a bit boring.