Having been on both five and six star lines, I have a pretty good idea of how a star rating should translate into the level of food, service, and accommodations on a ship. Despite my best efforts to truly appreciate Crystal, a few aspects of the above criteria were disappointing.
We (my wife and I) took this twelve day cruise in the Med mostly because of the great itinerary, which included half of every city in Europe we had ever hoped to see, and because the other lines rarely offer a Venice to Barcelona itinerary.
Initially we were very impressed, both by the staterooms, which are about 20% larger than what we're used to, and the friendliness of he staff, who try to get to know you rather than just saying "hello" as you pass by. In these two points, Crystal is great.
The food, while very good, was actually no better than Royal Caribbean, despite the fact that Crystal costs about three times as much as Royal. Yes, Crystal is all inclusive (other than excursions, more on that in a moment,) which justifiably accounts for about a 25% bump in the cost of a cruise, but at the end of your meal, you won't put down your fork and think, "Wow, that really was worth three times more."
Which brings us to shore excursions. If you've ever been appalled by the 200% mark-up on most cruise lines' excursions, but bit the bullet anyway because you wanted to make sure the cruise ship would wait for you, you haven't seen "nuthin" yet. The best I could figure, Crystal's mark up is probably in the neighborhood of 350%, and even that may be conservative. For this reason alone, if you're trying to decide between six star lines, go with Regent Seven Seas, which, for about the same price or a few dollars more, includes all excursions as well. If you're interested in the best value for your money, period, go with Royal Caribbean (or sister line Celebrity).
Would I sail with Crystal again? Yes, but only if they follow Regent's lead and include excursions.