Did this with my boyfriend for his birthday and just wanted to outline the fees that were not expected. You can find information at http://www.celebrationship.com/Groupon-FAQs-Celebration-Cruise-Line.html
Base price - $299 via groupon (expected)
Gratuities - $48 ($12/day/person)
Parking - $30 (mandatory valet; $15/day - v. long wait)
Island excursions - $68 (this was the most upsetting to us; for $34 each--the cheapest option--they bussed us to their resort where we got a towel and could choose a beach chair. Lunch not included, and all activities at the resort costed more)
TOTAL: $445 base price for two days for two of us
Although some blackout days were listed, some days (aka the one we wanted/reason we bought the groupon) were unavailable.
Wine is also very expensive on board, and you may not bring your own. There are a lot of activities on the ship: a casino, extra restaurants, a (small) pool and jacuzzi. Wifi is very expensive on board the ship.
Don't forget to bring power converters (two prong European) if you need anything and check roaming charges for your phone. No coffeemakers in the rooms, but coffee and tea are available 24/7 on the top deck, as well as fresh water. At times (I assume when reloading water onto the ship) water in-room is unavailable.
Frequent interruptions by crew members who want to "check in" on how you're doing and frequent "announcements" via intercom for the whole ship cut romantic moments short.
Servers were excellent, kind, funny, and made the trip memorable. Let us order as many main entrees as we wanted. Food was very good, although difficult at times for vegetarians, and not very many "healthy" meals.
Customs coming home took a LONG time to make sure to make your travel arrangements accordingly.
All in all, we had a good time, but would not use Celebration again because of the dishonesty of fees. It was very difficult to budget our trip without up-front prices, and this made the situation stressful at times.