This is a must-do for any big Harry Potter fan. I took my niece who grew up with the films and she loved it all. I've only seen a few of the films so what surprised me more was how much I also enjoyed it. The focus (unlike the theme parks elsewhere) is really on the movie making/production process and was quite interesting. In addition to seeing actual sets, costumes, props, there's lots to learn about all aspects of design, development, etc. There's lots to see! We spent about 3 hours (+ 30 minutes in the shop and did not stop for lunch) and could have easily used another 30 minutes. So managing your time is imperative (especially if you're on the tour buses which have set departure times on the tour). The one thing we'd wished for was a paper map that clearly laid out the different areas (it is huge!) to help us better pace our visit and make decisions about where to spend time.
Simply great experiance all around