I came on 5 November 2025 and had a brilliant time, I'd highly recommend a visit. I personally felt the entry fee of 220 pesos was very reasonable.
I was desperate to see the monkeys and after reading others' reviews, I got to the park around 10:20am. I didn't see the monkeys on my first full walk round the park but then I found them in several different places, and there were loads! I saw the most, and found them to be the most active, at 12:45, so I think it's really just your luck and being in the right place at the right time. My tips for keeping an eye out for them: if you see a human, staring up at a tree and smiling, I bet they've seen some monkeys. Otherwise, listen for rustling in the tops of trees, and keep an eye out for falling bits of fruit / nut shells - this could be the monkeys dropping them as they eat, which was a good indicator for me as to when they were about. I even saw a baby monkey before I left.
I also saw an iguana, a capybara, and loads of birds and butterflies.
The route is easy enough to follow - it's marked out on trees and along little stones on the ground, plus the reception staff will give you a map to use and return if you want. I took one and it was handy.
The route round is about 2km. It is mostly a path but be prepared that it's not a 'walking' path but rather a trail cleared through the trees to follow, at least for the longer biodiverse section. It's full of tree roots and steps, so unfortunately not for those who struggle with mobility and I'd recommend sturdy, comfortable shoes.
There's lots of information plaques, in Spanish, English and Mayan (I think), which talk about the plants, Mayan tradition, and the animals. Very informative.
I'll echo what everyone else says about mosquito repellant - come prepared and doused in repellant as they are everywhere.
The easiest way to get here is to drive but I got an Uber in each direction from the city centre and although it added to the price, it was convenient and I didn't have to wait more than 5 minutes for a ride home when I was leaving, even though the park is quite far out of the city. There's parking available for those who do drive.