Funny, I was there a couple years ago during NYE, and was surprised it was not busier. Don't get me wrong, it was busy, but I expected it to be worse. I did not have any issues with waiting for anything. It was comparable to when I normally go at the end of January, with the exception of the actual NYE night. I have heard the same complaints as from Dieuwer though, from a LOT of people.

As far as sleeping at night, that depends on where you stay 100%. I stay at the Tropicana, and it is never noisy at night. Like never! I stayed in the hotel zone once, and it was the noisiest hotel I have ever stayed in. It was so bad as far as food in that area, the noise, and the beach and water quality, I might never had gone back to PV (it was my first trip) had I not found Playa Los Muertos and the hotels along it. The only noise at night are the waves. Inland you are going to have a lot of noise though.