I've been and can recommend it highly. It's a really fun day out, but be prepared to do a lot of walking. The car parks are massive, and even once you've made it to the ticket office you've still got to zig zag down numerous ramps to get to the biospheres. It's worth every step though, you get to see many many plants that wouldn't normally grow in our climate. A word of warning though, try not to go on a blazing hot summers day. The biospehres get more and more humid the higher up you go and it gets quite hard to breathe. Did you know that they filmed parts of the Ice Palace scenes from Die Another Day inside one of the biospheres? Another good reason to go!