How I rate and review books on Goodreads

Recently there has been a big furore about reviews: fake, real, paid for honest reviews, paid for fake reviews and the whole attacking/commenting on authors saga. But what if you just really love to read and to tell your friends and followers about worthwhile books? 

On Goodreads, I'm one of the top reviewers in South Africa  (16th over all at the moment). Because I hate reading the whole plot in reviews, I keep mine very short. However, I often go back to my old reviews and ratings and wonder whether I should change them. I also often wonder how my ratings will hold up in a few years. 

The way I rate books is very subjective - and I don't think a lot of people can say their's are not. When I review and rate a book I really do try to focus just on the book itself - language, readablility and plot. But it is also influenced by an author's other works, what else I read recently, other books in the genre and obviously my mood.  

I've also recently started using Booklikes, but it's still quite new and a bit harder to use at the moment.

How do you rate books? 

Please remember to review A Grain of Sand.