Trip itself is very nice, especially for the Harry Potter fans. Takes over an hour to get there and back with the London's traffic. However time passes by fast as the Harry Potter movie plays all the time. Downside of our trip was weather. It was close to 90 in Farenheit and the air conditioner on the bus could not cool down the second floor properly. Especially that affected as on the way back as we had to seat in the bus over 10 minutes with the engine off and no cooling whatsoever. I had to go and ask driver to start the bus and turn on air. However for some reason he did it only on the second request and than turn it off again in few minutes as we were still waiting for some passengers in the group. Just to be clear the temperature on the second floor of the bus was reaching above 100 degrees on Farenheit...
Again - all this had nothing to do with the Studio itself but more curtacy from the driver would be nice. I understand people in London are not used to hot weather but still...
Another comment is about food. There are two places to get it in the Studio: one right before you enter the exhibition and one like hall way through. We asked the person at the Information desk if they are the same. He said yes. So we decided to eat before entering the exhibition... WRONG! The cafeteria \ restaurant half way through the tour is much nicer, less crowded, Harry Potter themed, had Butterscotch ice cream and drinks, had nice view on Harry Potter's house and 3 level bus, etc. In my opinion this was the place to it - not the basic standard eatery in the main entrance hall...
Otherwise everything else was great. Staff inside of the exhibition was very knowledgeable, going deep in the details on how prompts were designed and built, if you ask them. Kids loved Broom Stick flying green screen experience (kind of expensive after all as each poster or movie cost GBP 20 or 3 items for 50).
Overall trip was nice and I would definitely recommend it if you are into the Harry Potter movies or just into the films production / behind the scene experiences.