In a way, The Overstory would have deserved 10 stars just for the respect that I felt for Richard Powers after finishing the book. Without a doubt Powers has done a tremendous amount of background work for the book, and at least my expertise is not sufficient to prove any of his claims wrong.
There are as many as nine protagonists, who at first seem like a motley crew, but most of whom I grew fond of surprisingly strongly when the story progressed. After all, it's as much a story about people as it is about trees. The book is long and slow, a little like the trees themselves. The metaphor is hardly a coincidence. And no, the book isn't suitable for the hasty. You really have to stop by it to understand the wisdom that is conveyed by it. The same thing is urged in the book every now and then: if you stop and listen, you can hear the trees talking.
Powers invites his readers to learn more about trees, so that we could learn to understand and respect them. Still, the book doesn't preach, but really inspires to look at trees in a new way. That's what happened to me, at least. Sure, it also happened to me that from time to time I felt buried under all the philosophical reflection and the avalanche of information. I’m sure there’s a lot more to realize in the book for re-reading.
The title of the book is apt when playing with the ambiguity of the word "story". A small but charming detail.