First off, I would like to say that I selected Constellation because I was travelling with an 8 and 12 year old and had heard that this was a good option...More about that later.
Embarkation was not glamorous, but was quick and efficient. We chose Celebrity over Crystal b/c we were told by a travel agent that they are better for families. Thus, we afforded ourselves the Royal Suite and still came out significantly better than Crystal's prices. The suite was well-appointed - B & O stereo, 2 large flat-screen TVs, nice woodwork, walk-in closet, nice marble bathroom with a large tub (bring a bungee cord for the bathroom door, tho - a design flaw - it slams all night long). Butler service was helpful and made a nice difference for us in terms of unpacking/ packing, although I will say that at first the butler told us that he could not help us with packing b/c he had too many other suites to help and when we were clearly disappointed and he still had rec'd his tip, I think he thought better of it and decided to help out. I was happy to have the Royal Suite and it worked out well for a family w/ 2 young kids..there was a nice dining area for bkfst room service. I checked out the regular rooms and those were light and bright and we would have been fine in those as well...but if I had to do it again, I would still go for the Royal.
Food - San Marco feels like Red Lobster or something of that level. Iceberg lettuce, weak sauces, definitely not a gourmet experience, but passable. Ambiance was okay. We had a very lousy table at first in front of a kitchen entrance. I was surprised that having the Royal Suite gave us no better seating/reservation privileges in any of the dining facilities. Oceanliners IS indeed a fine dining experience, but we were only able to access it twice..would have gone more if we could have. Breakfast was fine everywhere and there were many choices, depending on how much time you wanted to spend. I was surprised that I was impressed by the ship's theater and entertainment. It definitely added to our evenings as we do not go to casinos or cigar bars...the other bars were WAY too smoky for our taste so we didn't go even though we go out to bars at home!