Having stayed in a few places in Montezuma, I can say that Luna Llena is my favourite. Not far up the hill that leads north out of town, it's priced between the low and mid range for the area, depending on what room you get. There are inexpensive dorm beds, more private rooms with shared spaces, and at least one room with a private shower and bathroom. Since that's the room we stayed in, that what this review is based on.
Luna Llena is comfortable, clean, and terraced, with reception, shared lounging areas and the kitchen, and the dorm rooms all in the same building right up at the top. There's a great view of the sunrise through the trees, and having the lounging areas and kitchen in such close proximity makes it easy to meet other travellers, or make food and wander off to your own spot. I know that the management has little control over the quality of its guests, but when we stayed there there were several really lovely guests with who I remain in touch; the sociable layout of Luna Llena really helped facilitate our meeting.
Luna Llena does not pretend to be a high-end spa or resort, and it sits beautifully in the trees, so you should expect simple accommodations (and that is not a slight, just an observation - and why travel to Costa Rica to sit inside?) and the likelihood of wildlife visitors outside of your room. We encountered titi and spider monkeys, a coati, and a variety of birds - all at a distance, but close enough to make for great pictures. The folks at Luna Llena also hold the house rules regarding safety seriously, but that never stopped any of them from being pleasant and helpful. For LGBT* travellers, our hosts (and guests) were perfectly lovely to this gay tourist and his husband.
The hotel is also a short walk from the centre of Montezuma, its many beautiful beaches, waterfalls, and the refreshing Piedras Coloradas (on the way to Playa Grande). And though there was a water shortage while we stayed at Luna Llena, the staff went out of their way to make sure there was enough water for us to make meals and clean up.
We plan to return to Montezuma and Luna Llena. It's priced just right for what it offers and, like Montezuma itself, strikes a nice balance between rustic and manicured, busy and off the beaten track.