Understanding PaaS by Michael McGrath provides a lot of great information related to Cloud Computing, Software as a Service (SaaS), Infrastructure as a Service (IaaS), and Platform as a Service (PaaS). As you can tell by the title the focus is more on PaaS than the other two. Even though the book is short compared to most book covering a topic, it seems that the authors intent is to provide you some great information about the benefits of PaaS, provide some good examples on how to start experimenting with it, and what you need to think about when you are designing the architecture of an application to run in the Cloud. If you are a developer or manager looking for a quick introduction into the benefits and what you need to think about when creating application to run in the Cloud and dealing with organizations that provide PaaS capabilities, then this is the book for you. If you are expecting this book to provide complete details of everything to do with Cloud Computing and PaaS capabilities (which is not the intent of the book), then you should look for something else. I really enjoyed the chapters on Architecture that talked a lot about what you need to be thinking about and the examples that are provided.
From first hand experience I have noticed the trend for the internal IT organizations are starting to host their own PaaS capabilities and share them between all of the organizations instead of maintaining servers for the specific groups. I can see the benefits of this and I understand the point that the author makes about the fact that this might not be the best idea due to the amount of up front cost to truly support PaaS capabilities. But it is a step in the right direction by providing the ability to customize the Platform that you want to deploy your application. I have run into the situation where at the beginning of a project your platform was defined one way and then it switches. The time it takes to re-image servers, setup accounts, and the rest of it is very time consuming. Where if you are dealing with a organization that provides PaaS capabilities you could just request the new requirements, which they probably already have a VM setup, and start deploying your application within minutes. The author does a great job with the examples and shows how you can work with a PaaS provider and GitHub to deploy your code.
If the book sounds exciting and you are interested in a quick and well presented overview of PaaS, then this is the book for you.