I've done it before. I'm about 50/50 on the value vs. price of it. Unless you can fill the boat to spread the costs, its really expensive, IMHO. Seriously, the vantage point is no different than standing on the bridge between UK and France. That's where it parks.
The skipper can make or break the experience. My captain was a lot of fun and took us on a tour before we parked for the fireworks. My biggest downer on the whole experience, besides the price, is that if the prevailing winds aren't in your favor, you will see NOTHING. Between the barge and the fireworks, its a lot of heavy black smoke. If the breeze is taking it away, its great. If its not, you can possibly have it all directly blowing on you and you simply cannot see a thing. This almost happen to us and the wind changed just before it all got to us.
One other issue is transportation after you are done. By the time you get back to the dock and disembark, you are now at the Yacht club with a long walk back through Epcot to get to the buses. I elected to get a cab for $20 back to my hotel right from the hotel. That was the best value of the whole night! :ROFLOL: