I booked three nights with my 8 year old son and overall we had a great time. The food was good as where the facilities. My son and I both enjoyed the water slides, which was our main attraction for the booking.
The only negatives I have are not from the stay, but from the things not explicitly stated or if they are, not obvious, at the time of booking.
So, be aware that if you are driving by yourself to the hotel, parking is an additional charge. it's not much, but three nights added £15. Also, Wifi is a paid for service in your room and only available for free in the lobby. Finally, be aware that when you book a particular room, it is only a preference. This hotel and other like it are package holiday destinations too and are going to be full, so you may not get your preference. In our case, we had booked a room with twin beds, but we were given a double.
The staff were friendly and helpful, from check-in through to the life guards and the catering staff. Of all the hotels I stayed with on our trip, my 8 year old said this was the best. An added bonus was that the beach is only a five minute walk away, so when the pools shut at 5pm, it's easy to spend some more time in the water on a sandy beach.
Overall, I do highly recommend Laguna Park, with just a couple of caveats.