Although this is a great attraction at a good price. 50,000 idr per person. We did see quite a lot of aggressive behaviour from the monkeys (admittedly this was due to a human interfering) however they can easily jump on your bag and un zip it or take water bottles and phones out of your hands! They are cite to look at at but make sure you keep a distance and don't have valuable showing invade they want to play!
There are signs before you go on advising you on how to be safe :)