I did not enjoy this as much as I thought I would.
Just to be clear, I have read Harry Potter before, but I'm on a bit of a nostalgia reading spree at the moment, and I've wanted to re-read the series for a while. Harry Potter! I thought, optimistically. It'll be awesome! Magic school! Evil wizards! And so on.
But reading it directly after Philip Pullman's YA series His Dark Materials kind of spoiled it for me. It really showed up just how superficial Rowling's writing is - we don't get any kind of insight into Harry's emotions, or any substantial description of the really cool stuff. What's it like to play a Quidditch match? Where's the feel of the breeze in your hair, the exhilaration of being fifty feet in the air? Or the Forest at night - the deep silence, the blood-freezing horror of that slithering in the dry leaves? Where, in short, is the atmosphere?
I'm also extremely surprised that no-one has sued Hogwarts for negligence yet. Sure, it's a magic school, you expect some dangerous stuff to happen...but, seriously, who leaves a bunch of children who've just discovered they have magic powers unsupervised in the vicinity of actual working flying broomsticks? Or leaves a dangerous object like the Mirror of Erised just lying around? Or hires a teacher with a Dark Lord hidden under his turban? The Almighty Dumbledore seems not to have seen that one coming.
My point is, reading Harry Potter and the Philosopher's Stone back as an adult highlights so many things that stretch its credibility to breaking point that it's just incredibly hard to take any of it on faith any more. The writing is mediocre at best (although there are a couple of laugh-out-loud moments), and though the story is enthralling, it relies on far too many gimmicks and coincidences to be completely satisfying.
The rating is mainly nostalgia talking.