I don't know, maybe it's me, but it felt a bit apologetic. Hey, if a reader doesn't connect with the material, they don't connect. I've loved books others have hated. I've hated books others loved. I don't expect the author of a book I hated to say I'm sorry for wasting your time. It was my choice.
Actually, I've never really understood people who say they read the entire book then post a negative review. I know pretty much about ten pages in whether I'm going to read further. If it's bad, I stop. And I don't post a negative review, because that's my opinion.
I think we've lost the core concept of a review: it isn't to say whether I liked it or didn't, it's to give people an idea of what the book is about, it's tone, and perhaps some commentary on how that was accomplished so that others can make their own decision on whether the book might be worth reading or not. Now I see things like: I don't like sex in a book, this book has sex in it, this book sucks.
Ultimately it's all opinion.