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)
not too bad; one big bed and two bunks which can go up and down; view of ocean is nice. intercom interrupts a lot, and water sometimes works. sink sometimes only has scorching hot water. european power plugs in cabin, and one american plug in bathroom, which does not work. no coffeemaker.