Matala Beach Caves are interesting to be seen and investigated. You need to pay few euro fee to get in. I think it is reasonable because on the other way people would go in to camp and none would be able to go and see the caves. Worth of paying and visiting.
Pack up some attitude for the filthy toilets, broken dressing rooms and huge crowds; then you'll be just fine. There are plenty of taverns and hotels which services you are of course able to use when being their customer.
It would be interesting to see this place in March or October when there are less people...
In Matala you can see beautiful street art on the walls and on the street, just look down where you walk. I think this is the best book shop advert I have ever seen!