We had a great time. It was £39 for a family of 4 and we arrived at 10am and left around 3.15pm, but didn't even get to look at the 'old' stuff on level 0.
I think the 13 yr old would have found it a bit boring but he enjoyed the animation workshop.
We started with a tour of the DinoJaws exhibition, these animatronic creatures were great and very big, then into the Planetarium to hear about Ursa Major (The Bear), then some lunch (this was a bit pricey and not much to choose from, but it tasted ok). Then off to the animation workshop, whilst the youngest went around Kid's City for an hour. Kids City is a makeshift town for the kids to explore and learn in. There are shops, a hospital, cafe, garage etc. and in each you can dress up and become a docrtor, shop keeper, cook and so on. Each of the buildings are linked via a telephone system and you can call each other in the other buildings. Met back up and went around the Things About Me exhibition, which is all about the human body and senses. Finally went into the theater to see the Big Bang demonstration. Fire, explosions, flashing lights. The youngest one got restless by then so we nipped into Wing Yip (a wholesale Chinese supermarket) nearby, and then into Wing Wah's for some tea.
All in all a very nice day out considering the weather!