Microsoft deal in in-house, licensed and proprietary productivity systems. So this product treads a fine line between offering hosted services and limiting those services to protect their licence income from related products. You might want to stay with Microsoft if you have a previous investment in Office files, or you value employee understanding of the office formats. Brett makes a good job of explaining the features present and not present in Office 365, and how they compare with the various Microsoft licensing models.
Brett is out of the Microsoft stable; he does not make direct comparisons with competing solutions, apart from occasional references to the superior image of MS-hosted businesses.
If MS Office 365 is for you - and it is worth buying the book just to assist in making that decision - the next question is: How to set it up.
Brett's experience shows here; he navigates us through the different options, even making honest comparisons of subscription prices with licence pricing. The book helps you match the size of the Office 365 set-up to the size and type of your business; choose the best configurations, and then set up the administration.
Buy this book if your business is an existing MS user and you are evaluating cloud or SaaS options. But probably not if you are looking for open source, crm or collaborative software systems. Buy this book if you want to judge the most cost-effective way to move forward with MS Office; but probably not if your requirements go further than office productivity and extend to hosting a commercial web-site or business systems. Buy this book if you are newly tasked with setting up or administering your Office 365 implementation; but probably not so useful if you are already an experienced Office or Sharepoint administrator.