According to the prerequisites, "HTML5 and CSS3: Developing with Tomorrow's Standards Today" is aimed at developers with a good understanding of HTML and CSS, as well as those having a basic understanding of Javascript in general, and jQuery in particular. I would echo these sentiments; it's not a book for the complete beginner. The book leans quite heavily on jQuery, and while there's a primer in the appendices, a reader who does not have appreciation of Javascript -- and its potentially odd-looking syntax -- is as likely to be left bewildered as he or she is enlightened.
The book begins with an overview of new additions to HTML5 and CSS3, and deprecated tags that are commonly encountered, along with a caveat that these are specifications that are in development, so could change at any time.
"HTML5 and CSS3" is presented in three parts. Broadly speaking, the first part covers new semantic and structural elements & attributes; e.g. header, nav and section elements. Part two covers more presentational aspects such as the canvas, audio & video elements, and new capabilities of CSS3 such as rounded corners, gradients and drop shadows. Part 3 covers aspects of "HTML5" which are neither markup nor presentation, and have either been spun off from the HTML5 specification, or which were never part of the specification in the first place; these include local storage, web sockets and geolocation.
Each item is introduced in the context of a realistic example, covering not only the "what" of new features, but also the "why". I found the style quite abrupt, and occasionally lacking enough introduction to blocks of code, be it the HTML, CSS or Javascript that peppers the pages. Similarly, I sometimes read comments within the text that didn't seem to follow or seem obviously connected to the preceding block of code. As noted before, this book is intended for intermediate developers at least, and I think a degree of inference and internal linking of dots is expected.
Most features are accompanied with a fallback proposition for browsers that don't yet support the item under discussion; these fallbacks are largely Javascript dependent, and are accompanied with examples of how to detect whether the feature is supported. This was one of the most useful aspects of the book, I felt, as I've found it easier to find out what "HTML5" can do, than I have found material that enables me to use the features with confidence that my pages won't be unusable for a significant number of my audience.
The author also tries to keep the accessibility aspects of new features in the reader's mind, both offering examples of how the new elements and attributes can help disabled users, as well as highlighting any downsides of the fallback propositions.
This book contains a good amount of useful information for the developer who wants to get stuck in to using HTML5 and CSS3 right now. However, each feature's coverage is short, before moving swiftly along to the next item, so this is something of a whistle-stop tour. Some work is required on the reader's part in order to make the most of what's presented, but it's certainly a sound launchpad for exploring the new frontier.