We went a few days ago. It's really beautiful and the DCs enjoyed it, but will not fill up a whole day. We were there for 10.am and by 11.20 we were finished and eating our sandwiches in the picnic area. I persuaded DCs to double back to the coral reef area to see the fish being fed, but after that they were ready to leave. (DS1 is 8 and DS2 is 6)
I think it was worth a visit, but is not as good value as the zoo. I had 2 free child vouchers from primary times magazine, but could only use one per paying adult, so as it was just me with DCs it cost us £22 for 2 hours entertainment.(I would NOT have paid the full £31 price for the 3 of us)
I think the fact that we had also paid £7.50 to come into town on the bus made me feel a bit Grrrrrrrrrrrrrr about the cost of the whole trip.