In my opinion, I think the only movie that I have liked so far is the Deathly Hallows. I have seen all of them and I just didn't feel like they lived up to the books at all. I do think you should watch the movies before you go so you will know what a lot of the things you will see are. Like Buckbeak, the flying car, Zonko's, Honeydukes and so on... Also the ride is pretty much based on the movies so I really think watching them will be worth the time.
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