First of all, I like the title god is not Great which alludes to the Arabic Allahu Akbar (God is Great).
Secondly, Christopher Hitchens is a polemicist by his own admission and one should keep that in mind while reading this book. This is not an analysis of religion (going over its evolutionary origins for example) or even a high-minded atheist response to religion like The God Delusion by Richard Dawkins.
Keeping that in mind, I actually liked god is not Great. Hitchens is a good writer. He knows how to turn a phrase and his allusions to literature references were also clever and interesting.
His case against religion is flawed but not completely wrong. There are lots of bad and evil things the religious and organized religion have done or condoned. Despite all those issues, I think we can only say that religion does not make one better or worse. This in itself is a major indictment of religion.
However, as discussed in Religion Explained, religion and religious beliefs have natural evolutionary origins and arise out of how our mind works. So religion is here to stay. Even people who do not consider themselves religious usually have beliefs that can be classified as religion.
You can read some excerpts from the book on Slate.
When I was reading god is not Great, I decided to live-blog (or live-forum) it at UrduWeb.