Some travellers tell of a bad experience. Most of the time it's the organising agency which is at fault, not the trip. The caves are magnificent. The crossing on the underground river, in a small boat, is fun, but not really educational. The PPSRNP is classified as a UNESCO World Heritage Site and I strongly recommend visiting it during your trip to the Philippines.
For more freedom and less expense, we preferred to not use an agency and to visit the site on the Monkey Trail. I loved this opening in the jungle. You go above the karstic formations on wooden bridges. The noises of the jungle are incredible and there really are monkeys everywhere. By the way, it's best not to attract them as they can become aggressive. During a stop for a snack, a few of them came close to us, attracted by the food and we had to package everything up quickly.