yeh, we've been a few times - used to have a annual pass. I think personally it was better when it first opened, theres a few bits that are broken and have never been fixed . OTOH, its massive! Its basically got 4 large areas with different themes.
Fire: nice tornado feature which generally works, and lots of things you can get to do things to and understand without reading all the waffle. probably aimed more at the slightly older kids, but the little ones will prob enjoy too.
Earth: lovely little ones area with sand and wheelbarrows and lots of things to turn! nice photo ops too. The JCB's rarely work, and if there is one that works you can guarentee there will be a queue a mile long for it. some good bits for most ages.
Wind: little bit dull, but nice enough - lots of stuff broken tho in this one.
Water: this one my kids love - probably a good idea to either take some spare clothes or go to this one last. There are some aprons, but the kids are invariably soaked when they come out. LOTS and LOTS to do, spraying, sprinkling, pouring, you name it. Theres a fabby little walkthru to get to it, that really looks great. Theres a water rocket, fairground sprayer, a set of locks and boats, water turbine, and a few other bits. We usually spent about an hour in this bit.
the complex is huge, and if you've got a wobbly walker, i advise a buggy/chair, or they can loan one - they are a bit basic tho. the place is also quite cold even on sunny days so take a coat with you. The massive furnace-y thing is half interesting but the kids may get bored/scared halfway thru as it drones on a bit then gets really loud. the place is extremely accessable. i advise dipping out on the cafe tho, overpriced and sells utter rubbish - better make for an McD's if poss theres one about 10mins away instead.
They also have a fantastic outdoor play area thats got something for everyone and well worth the extra bit of money.
hope you have a great day, HTH XXX