We stayed here for 3 nights over New Years and we had a great time! This is more of a backpackers place, so it's not for people who are looking for anything fancy. We really liked the location, the vibe of the place and the people. We stayed in room number 6, which have been refered to as the "honeymoon suite". We really liked our little hut - it had fantastic views and a patio area with a table and chairs were we had breakfast every morning looking at the ocean (and the monkeys jumping around). Our hut had a sink, but no toilet - you had to share that with a few other people.
On New Years Eve the owners put together a party at the hostel and gave out glow sticks to everyone. We then had a glow parade walking down to the town center where there was a huge street party, bands playing in the street and bonfires and fireworks at the beach. It was a blast!
Pros: Great staff, great location just outside of the bustling town center, nice views, good people, great monkey watching, you feel like you live in the jungle.
Cons: Very warm at night (despite the fan), bugs (you are OK if you sleep under the mosquito net), monkeys that keep you up at night, shared bathrooms.
Over all we were very happy that we stayed at Luna Llena during our visit to Montezuma, however, after 3 nights we were ready to move on to a more quiet place with airconditioning :)