My partner and I (both in our 30s) went on the Independence of the Seas for the first time. We are both busy teachers so we just wanted a short break at half-term. We were also first time cruisers. We had a thoroughly enjoyable time. The service was excellent, the food was excellent. Snacks and soft drinks were available at all times. We opted for an inside stateroom to keep costs down. The room although plenty big enough for two people, was perfect just for base on such a short trip. On a longer cruise, I think a bit more room would be advisable.
We opted to eat in the King Lear restaurant for breakfast and dinner each day and we were stuffed - the food was delicious. Alcoholic drinks are quite pricey but we had anticipated that. If you don't drink alcohol, you need not spend any money at all because so much in included in the price. The cabaret acts were slightly on the cheesy side but that didn't bother us either. If you have children, there is plenty for them to do.
At the ports we stopped at (Le Havre and Zeebrugge), it was easy to just get off the ship and get into town on foot (you don't need to buy a shuttle pass if you are fit and like walking). We left the trip feeling relaxed and recharged, we had a FABULOUS time - highly recommended for a short break.