I've spend two times in this hotel. This year (2011) and last year, both times in June.
Though this time I liked it less, it is worth a try if you are after a budget variant in Kas.
There are two major areas to stay in Kas - the peninsular, which is about 5 km long, and the town itself. Both have their pros and cons. As I love staying at the peninsular, the Aquapark hotel is a choice. It is located on the very top of the peninsular and has the biggest territory in town. There are several swimming pools (one is rather big), they are arranged in cascades. There are also two water slides (operated from about 11 till about 17... some reviewes said they are inoperable, which is not exactly true). The territory is really big, but a little neglected in some places, so those, who may like park-type hotels, may not like it. However, there is always a way to keep out of the crowd, if you don't want to get in touch.
The breakfasts and dinners are OK, they make grilled meals some days.
The beach is a platform, the depth starts right from the ladder. I haven't seen too many people in the beach both times of my stay in the hotel, so there is always a way to find a cot. The water is really clean in the area, and the beach is a Blue Flag beach. It faces a huge mountain of the mainlands on one side and Kastelloriso on the other, so the swim there is really pleasant. In June the water temperature is already OK.
The thing to be aware of is that not all rooms are equally good. First time last year I was offered a corner room facing the parking lot, and it had some problems with the sewage, So I finally changed the room to the facade part of the reception building. This room is quite OK. The furniture is rather old and basic, but if you are not looking for luxury, it is OK. The view from the balcony was really relaxing. The second time I was not so lucky, so the first room I was offered was again - the same corner room facing the parking, the second one was the same room location, but on an upper floor, and only the third offer was rather suitable. It was in one of the buildings facing the beach platform. It provided a spectacular view to the sea and mountain. However, it was on the ground floor with no balcony of its own, and I guess there was something leaking on the upper floor, when people over there used their bathroom. the furniture was also very-very basic and far from being new.
I guess this time it was because the hotel was crowded. There was a real irruption this time (unluckily there were some noisy Britains, who shrieked the whole night through until 3 a.m. at the pizza bar). So probably they did not have a good alternative choice of rooms.
However, this hotel is worth a try if you travel on a budget. Kids could certainly have fun there, as there is an evening disco, animation and water slides (those the only slides in the peninsular area, plus there are four in one of the city beaches).
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC