The ship and the cabin were very clean and well kept. The cabins were evidently older but still in excellent shape. The dining experience was great with friendly staff and outstanding service in the main dining room. The buffet on the cruise wasn't as excellent but was still good overall. As for on-board entertainment, the ship had plenty to offer. Trivia, mini-golf (kinda lame), production shows, band performances in the centruum, etc. All the performances were great. Comedians: late-night comedy was hilarious! Music Shows: Musicians (except for a couple singers) we're absolutely incredible - very high musicianship. Service was great at the main dining room (Tides), Chef's Table, and Izumi (Japanese Cuisine). Food at all the previously mentioned placed was also outstanding. At Chef's table, the head chef even came out and gave us the recipe for the Smoked Tomato Soup we had in the 2nd course. Definitely recommend the Chef's Table experience if you can justify the expense.
Be careful with the shore excursions the descriptions aren't very clear. EcoTrek to Bamboo Falls requires water shoes. The Turtle and Shipwreck extrusion in Barbados was amazing - be aware of the drinks.. they're very generous with the alcohol.
I would definitely do this cruise again given the option. As i haven't traveled with any other cruise lines, I cannot comment about the difference between lines, but Royal Caribbean was a great cruise.