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I've read Harry Potter & The Philosopher's Stone, and seen all the films to date.
Do you think it is worth reading the Chamber of Secrets and The Prisoner of Azkaban, or 'skip' to the 4th book?
All replies welcome.
YES. The 2nd book is pretty good (scary, or at least when I read it!) and the 3rd is my favourite. Read them, they flesh out characters, explain much, and introduce many characters, and important things. READ THEM!
The earlier books aren't that long anyways... so it shouldn't take too long to read them both, unless you're a slow reader (not saying you are). The Chamber of Secrets (#2) adds a bit of history to existing characters, but personally I don't think is vital overall. But since it's only a few hundred pages in length, you might as well get it out of the way. The Prisoner of Azkaban (#3) is a must, as it starts getting into the story line and characters who become quite important for the books following.
Really hard to say more without giving away spoilers.
Everyone's entitled to their own opinion, even if it's wrong.