We loved watching from the Poly. I don't think the music was piped in, but it's a great more-or-less straight on view, and you can see some of the castle and it's lighting as well.
We sat on the beach, in the lounge chairs that were out there, very relaxing! Something about the beach, the bungalows on the water, the way the fireworks reflect on the lagoon, it's just very nice the whole thing.
And some nights the Electrical Water Pageant starts at about the same time as the fireworks so you get an amazing double show going on simultaneously.