bianca.simas 
Why would you write a book review? To tell anyone that reads it, how do you felt about the book!
It’s not that you are not allowed to dislike a book but, if you just give 1 or 2 stars and not say why are you doing it, you are no better than a teacher giving you a grade without showing your errors.
You are not giving the author a constructive feedback, you are not helping the author to evolve and you are definitely not assisting a fellow reader to make their choices regarding their next book.
So ask yourself: Why are you really giving this review?
Thanks for the interesting and useful information, it will give me new knowledge.
Thanks.
Interesting solutions
You are absolutely right. There is something in this and it is a good idea. I am ready to support you.
In my opinion, this is a very interesting topic. I suggest you discuss it here or in PM.
Guys, is this an effective method or not?