We did one for the first time during out trip a few weeks ago. We loved it. We did the cruise for 8 people and it was $334, but was the highlight of the trip for most of us. We originally booked it by calling (407) WDW-PLAY, but then re-booked it soon after by calling
DVC member services because they had a discount offer. (Without the discount it would have been $371) It was perfect for a group of 8 people and everybody had a ball. We were surprised that we got a tour of that whole lake, going all the way over to HS before heading into Epcot and tying up just past the bridge between France and England for the show. We didn't add anything extra (like food or wine) to our package, but snacks were included with a cooler full of soft drinks and a basket of snacks including chips, brownies, rice crispy treats, etc. Our Captain (Captain Ron) was great, and really made it fun. He's done over 6000 of these cruises and did a great job. Our only warning is that it will spoil you for watching Illuminations any other way.
Here's a few of our pics: