We did a night walk starting at ~ 18:00. The whole walk was a wonderful experience and we learned a lot of interesting facts about the different animals we saw and the forest itself.
Our highlights: We spotted a Kinkajou, two (green?) vipers (a baby and an adult), a scorpion (in the waiting area next to the reception :) ), a tarantula and some sleeping birds (incl. a toucanet). We also saw leaf cutter ants which we've already seen in many different places in CR and our guide provided a detailed and very fascinating description of the different ants in the colony. He was also very knowledgeable about the whole flora & fauna.
For our preferences the group was too large and there were many other groups in the park at the same time. Nevertheless it was an awesome experience and we would suggest you go there.
Long pants and closed shoes recommended. Depending on the weather bring a jacket since it was really windy when we visited. Don't forget your camera or mobile phone for pictures