We booked in advance at our local tour operator and got reduced rates, though still cost €66 for 3 adults and one child. There were a lot of hidden extras €5 for locker hire, €5 for sun lounge hire, €10 for a photograph and lots of opportunities to buy souvenirs and food. We had expected this so took a picnic, which there was no objections too.
The park itself is well maintained and has a good selection of slides. There were lifeguards at the bottoms and top of every slide which was good. Overall we had a thoroughly enjoyable day, we went in October so it was relatively quiet and didn't really have to queue for any of the slides. Think we were there around 4 hours and did every slide 3-4 times.
Only really grumble is the changing rooms were gross!
Overall a good day :)