We really enjoyed it. The food and service was wonderful. My parents still bring it up as one of their favorite meals. They do take the dining plan and it is two table service credits. You do get a Mimosa or Bloody Mary (if you want), an appetizer, entrée, and shared trio of desserts for that. We did it on our magic kingdom day and it was really easy just to take the boat right over for brunch.
added: I just read on a different thread that the brunch isn't included on the dining plan so I looked on WDW and it does show that it is N/A for brunch on the 2016 plan. We were able to use in last month (2015). Sorry for the out of date information.