I had great expectations for the Half Moon party, however it turned out to be a let down. I know some people enjoyed it more than the Full Moon party, because they told me as much, but I couldn't see the appeal.
Chrissy, Diana, Steve, myself, and an American girl arrived early via taxi. Images of a rustic setup in the jungle were quickly dispelled when we walked up the access road to see a ticket booth. We all seemed to have missed the detail of a cover charge, perhaps because it wasn't mentioned on the flyers. It was about $9, which included one drink. On top of the return taxi fare, the night was already shaping up to be more costly than the Full Moon Party. And then I saw the drink prices, which were about 30% higher than what you could get on Haad Rin.
The venue was not jungle-like at all. There were buildings, concrete, infrastructure! After a loop around the premises, it was clear there was little escape from the music if psy-trance wasn't your thing. I often enjoyed it at the beach, but I wasn't digging it at the Half Moon party.
Thankfully, they had a few fire dancers who provided much needed entertainment. It was probably the highlight of the night for me. Steve and the American girl left at 1am, and I knew I had to decide whether to leave with them or at 4am with Chrissy and Diana (who were trying to stay up all night as they had to leave Koh Phangan early that morning). I decided to stay longer, and almost immediately regretted it.
During those painful 3 hours, I saw the bloody results of a guy who got hit in the head with a bottle. I saw Chrissy needing to take care of Diana who accidentally had too much to drink. I had to stay under the roof of a bar due to pouring rain. I witnessed some girl seemingly start to bleed spontaneously (after a few minutes, a guy carried her down the access road as blood and tears ran down her face).
And on top of it all, when 4am rolled around, we didn't immediately connect with our taxi. Apparently she was waiting for us at the gate but didn't see us leave, so we waited around for 30 minutes thinking we'd have to pay for a new taxi to get back (which would've been VERY expensive given we were on a remote beach). While we were cursing taxis, I spotted the cool fire dancer and had my photo taken with him. I asked him how long he'd been twirling fire, and he responded a year and a half. He practices about 3 hours a day, every day.
My advice: Do not go out of your way to attend the Half Moon Party.