I took my 5 year old daughter here on a rainy Sunday and we had a ball.
The term 'museum' doesn't really capture what it offers. It is a hands-on, experiential place that covers environmental awareness, storytelling and scientific experimentation that was perfectly pitched for a 5 year old. I think it would appeal to older kids too.
It only opened 6 months ago and is in great shape. Everything is very clean and well thought out. There are plenty of staff on hand who all had great English and were extremely friendly. It feels extremely free and easy for kids to explore, there was almost no 'cannot' to be heard, which was a relief.
There is a wide variety of activities including interactive storytelling, a small wind tunnel where you can take your recycled good vehicles for a test flight (fun!), an amazing sandpit that (almost magically) creates contour lines on the sand to show when you create mountains and oceans (you really have to see it to get the full brilliance of it -I'm doing it no justice here), a window to paint on (see photo), a large magnetic marble run, an activity to draw attention to how many miles food travels to get to HK, a large video microscope with a massive selection of things to study and a banyan tree rope bridge to explore.
There are some excellent quality picture books distributed all over the place and a sweet little corner to read them in.
You can book in advance for a 2.5 hour session. It is extremely reasonably priced and the time flew by.
They plan to change the theme of the main 'experiment' room every 2-3 months and they are very open to groups of children from schools, other organisations.
I will go again, no question, and will be sure to take my daughter's friends along next time.