We loved the cave! We booked our tour through Tropic Tours which picked us up from our villa at Casa de Campo. Because we have 5 in our group, we got a private tour through the cave which was great. If you book with Tropic Tours, which I highly suggest, ask for Edward as your guide. Spoke perfect english, very knowledgable about the area and made our ride to the cave great. And after the tour, they took us to a small store in La Romana where we could buy local artists work.
The cave was beautiful. But very wet and very very humid. Don't expect a cold cave. Dress accordingly! The walk ways are well paved with hand rails and very well lit. Our guide was very nice and spoke just enough english that we could get the gist of what she was attempting to tell us. But we never understood when it was ok or not to take pictures. So we took pictures through most of the cave until she was shocked and said "no pictures in the cave" clear enough for us to understand. By that point, we were almost done. When taking pictures in the cave (when you are not supposed to!) don't use the flash. It really can damage the walls and makes your pics look way too bright. Go without flash and you will get some fantastic photos!