Time: About 30 minutes
When you know this exists in real life, there is no way you can't go.
They even have a Harry Potter store with every product relative to the books and movies you can think of! Consequently they offer to take your picture for free, let you choose your house scarf, and they will make it look like an action shot, all in hopes you'll like the picture they take better than the one you take and go purchase it.
We did, ours were a little blurry- but we were also traveling on a budget and decided we'd deal with the ones those nice teenagers behind us offered to take!
He hasn't even read the books, and still enjoyed visiting!
And even if fuzzy, can you honestly beat this image?
(Answer, yes, Jacob could have grabbed the other Gryffindor scarf once I explained why we belonged there with Harry, Hermione, and Ron)