- What you liked or thought about the book;
- How it affected you;
- How one may benefit from reading it;
- Who you think would enjoy it.
According to Sell Your Book On Amazon, it should ideally be a paragraph or two. Things that would spoil the suspense such as telling how it ends should be left out.
On the other hand, if you didn't like the book, it's better not to write any review because authors have feelings too and a bad book review can go a long way in deterring people from buying it. I learned this lesson early on when I first started posting reviews on Amazon for every book I read because according to Sell Your Book On Amazon an author should seek to develop a presence by doing a lot of book reviews. I inadvertently hurt an author's feelings who I met on MySpace by posting a review of her book when I really didn't like it even though I hoped I would. Regardless of trying to be nice and still be honest, giving it 3 stars (which according to Amazon said "I like it" when in my heart I would have given it one star) she saw it and was deeply hurt anyway. I felt awful and immediately deleted the review but the damage was done. (The only exception to this is if it's a very controversial book, for example, The Shack, where people seem to either love it or hate it and which has many reviews. In this case the controversy is what makes people want to read it for themselves and is a good thing.)
Since this incident, I try to read the book before I let the author know I got it. That way if I don't like it, I haven't put myself in an awkward position and choose not to post an Amazon review. I certainly hope those who read My Funny Dad, Harry do not have this problem, but just to be safe, best not to tell me that you have it until after reading it.