I'm brushing up on my Harry in preparation for this week's release of book 6, Harry Potter and the Half-Blood Prince. I listened to the audio version read by Jim Dale, who is a genius. Seriously, the Harry Potter audio books are the best I have ever listened to. His performance is superb, and if you've watched the movies, you can really tell how his voices influenced the actors portraying the characters.
I like the Harry Potter books a lot. Every time I start thinking that Rowling is just writing cute kid's books she surprises me....the structure of the books is excellent. Everything ties together and into the emotional climax/conclusion. I'm impressed that she dealt with a difficult subject (death) in such a mature, thorough way.
In sum, buy it. And then buy the next one.