Well, I'll start with, "Not my style of book." Literary, relationship/character-driven, adult. Those who follow my reviews know that most of the reading I do "just for me" is YA fantasy, generally with strong female leads.
That being said, this is well-worth reading. Rowling is a strong writer. Several phrases have stuck with me all week...a used condom on a step, glistening like a ___ coming out of its chrysalis. (Sorry, don't have the book to refer to for the exact wording.)
The characters were complex and interesting, though I didn't like most of them. I was struck by the bleakness of their lives; they weren't particularly happy people and not happy in their marriages.
I didn't see the ending coming AT ALL! Also fascinating that Rowling didn't tie everything up with a nice bow - life doesn't always (generally doesn't) have nice clean endings.
I recommend reading it at a time that you can spend several hours in a row. It was so complex that if I'd tried to read in 15-20 minute increments, I'd probably have gotten lost.