This was never my favorite as a child I would usually skip this, and rereading it again. It's still not my favorite. The Half Blood Prince is, in my opinion sandwich between two significantly better books. But it has grown on me I do enjoy the building of relationships between many people, and the revelations about voldemort's past or very interesting upon reread.

I don't know, maybe it's because I had the ending of the book 6 spoiled to me before I even started book 1, maybe it's because I've never had that large of an emotional attachment to Dumbledore, but the ending of The Half Blood Prince never resonated with me as a has with others.