Very short and very shallow. If I had to pay for this book I would ask for the refund, since you can get pretty much the same information from just reading few blog posts and Celery documentation.
In fact, after thinking about it - my biggest gripe with books like this is not necessarily their length or their level of deepness/shallowness. It is fine to be concise and there's nothing wrong in providing a high-level overview. The problem in my opinion is a contrast between very high-level chapters describing general approach to the distributed computing and very detailed chapters instructing you how to setup, for example, an account with AWS. Those two things are just not good together.