I was wondering what that was like myself. I have not been yet and have not yet fully committed to trying to snag a reservation for my spouse and myself, but I'll share what I have read.
Generally the reviews are pretty meh at best. I don't get the impression there is anything wrong with the food, wine, or viewing itself, just the general consensus is there is a very noticeable lack of top tier feeling to a top tier priced event. Pictures of the area with tables provided was described by one reviewer as "looks like the location for a dinner at a used car salesman's convention in the 1970s".
One reviewer listed out the all the food was just entrees and sushi from the restaurant presented as finger food and pointed out for the price of two you could order them all in the restaurant next door. A number of reviewers suggested the Ferrytale Dessert Cruise instead. All of the reviews were from last spring so perhaps it has improved since then?
I was looking into the Celebration at the Top because I want something with a certain je n'ais c'est quoi for our last night in the parks. It definitely does not appear Celebration at the Top is going to offer that.