The first thing is you get to book things 120 days out (if paid in full). You have a concierge shoreside team that you can email or call with questions, advice, suggestions, concerns, anything ... they are very good. As of now, the shoreside concierge is the only way to pre-book a cabana on castaway cay. Then your check in and boarding is expedited and you go to a little reception onboard where you meet your concierge hosts and there are reps from the spa, kids club that facilitate registering and adjust any bookings - they seem to have openings that magically appear for you. Lets say your dining rotation is such that the night you had booked for Palo is on a day where you don't want to miss the assigned restaurant, they'll change it for you in a jiffy. They have a folder for you and go over any details you want to. Then there is the full hot breakfast brought to your room if you wish as long as you order it by 10 pm the night before. Your concierge host is available to you via direct line until 10 pm every day if you need anything. There is a concierge cocktail pre-dinner reception during the cruise where characters make an appearance.
Don't know what room you are staying in but the amenities go way beyond the room IMHO.
I'm interested to see what differences there are on the Dream with the lounge and sundeck ... but the real perk for me is the personalized attention and cutting through the anxiety of the "lines and waitlist" mentality like trying to book popular things and being locked out ... I guess I'm trying to say you are paying in part for "access" - if that makes any sense ... like the world of politics