We did this on our May trip this year and my DH and I enjoyed it --- my DS9 at the time --- wasn't thrilled with it. The food and refreshments were excellent and we enjoyed the fireworks. They also give you a light up necklace and a souvenir pin which is also nice. At the end of the cruise as we were leaving the ship they were basically handing out the leftover mickey bars, etc.... The night we did the cruise they did have a Photopass photographer available onboard.
There were a couple of things we found. There isn't a lot for kids to do on the cruise so if you have kids that need to always be busy it may not be the best option. There is a scavenger hunt that requires using a UV flashlight to complete. They don't have enough flashlights for all the groups on the cruise so people were supposed to do the hunt and then return the light to the CM so that others can do the hunt as well. There were a number of adults-only groups who held onto the flashlights for the whole cruise but didn't do the hunt. This meant there were a number of groups who never had the opportunity to do the hunt at all. Our DS wasn't interested in the hunt but there was a family with 3 kids next to us who were really disappointed that they didn't get to try the hunt.
During the cruising part the guests were spread out on both sides of the 2 decks and there was lots of room for everyone. During the fireworks everyone goes to one side of the boat and it felt very crowded.
