This is a nice book to read and learn. It is written for the x86 and x86_64 technology and does a good job to explain how things work. I enjoyed reading about the xen architecture and the CLI. I didn't like reading about the enterprise grid. I could give it a higher review but the fact that it was released at the turn of technology (oracle releases VM 3) makes me think about bad timing. The book could also be more verbose. One can just read oracle documentation to learn most of the topics that the book explains.