Hellmark,
I must admit that the only book I have is The Philosopher's Stone. I started but I didn't finish it. So my judgment on the series is still based on this book alone. Going off topic here but one can imagine much more than cliché, old, dusty concepts such as a witch and the broom and magicians with pointy hats and magic wands etc.
Anyway... It ended up by not being my cup of tea, really.