Personally I felt the last book was not so great. In the company of myself I call it Harry Potter and the Overly Long Camping Trip.
But really, as a book series I think it's best enjoyed in the company of others so that you can share in the story. It's like going to a movie with friends. You can talk about it after. I think that's the best part of the books. Without that, I don't know if I'd have gone through the effort of finishing them so I can see why, at this point and time, someone wouldn't really care for them.