Do you have to have read (or like) Harry Potter to appreciate this? I read several chapters (8 or so) and I actually found the story very distracting from the rationality message.
I would say yes. So much of the world is taken directly from the actual Harry Potter books and a lot of the fun is to see the effect new Harry has on the same world.
I would say no. There are readers who haven't read the original book, and still enjoy the fanfic. I agree that much of the fun is taken away from those, though.
You need some familiarity with the world, though, to get many of the jokes ("In what universe would someone like Hermione get sorted anywhere but Ravenclaw?" - "Ron's just..." "You just don't see any good reason for him to exist?" "Yeah.") and also knowing the story allows you to anticipate certain realities before Harry gets to grip with them. For example, we all know that Voldemort is Professor Quirrell, but Harry doesn't (at least not as far as I've read).
Background knowledge definitely helps with the enjoyment - and imho is the only reason why you'd want to read the JK Rowling books or watch the movies! I mean, I don't dislike the books (I've read them), but they're not much more than decent entertainment (with some of them dragging on, and on, and on).
