This is my GoodReads link, they're now owned by Amazon like Audible. Sometimes I make a book review extremely thorough and even more words than seems appropriate for GR or Amazon - those go up on AmberUnmasked - like Canary or Blanche on the Lam. Then I usually go to GR and say "my full review is on my site..." with a link and give only a synopsis. That's because if I'm being critical and detailed and possibly tearing up something I didn't enjoy, I don't want to wreck the book sales on Amazon. I'll post what I did like and link to a fuller, more thorough analysis.
Is that fair? I think so, especially if I'm reviewing a friend's book. I want to be able to be totally honest somewhere but still support their careers. Honestly, I don't think anyone likes a bad review, not even friends when I'm trying to point out troubling issues. If it's severe, I'll even ask them if they want to read it first in an email. I love my friends even if I don't always like how they handle characters. I can always learn something from them even if it's I don't like this and I'll never do this to my characters without good cause.
The bigger potential problem is that Amazon deletes reviews by friends of the author if they find out. People tend to network within their own industries. Writers will get to know other writers, and yes, become friends. Writers might also know better what works about a book and what doesn't. Yet, Amazon doesn't want those reviews to count as legitimate since positive reviews over a certain number bump up the presence of the book in their listings and searches.
Anyway, the link above is for the list I've reviewed and the most recent book I finished over the weekend should appear at the top. Only one criticism and that's the lack of diversity, but otherwise, a great read.