I’m sure there are a number of great books out there that talk about HTML 5. I will be recommending this one to my friends who want to get up to speed quickly. This covered exactly what I needed at this point and gave me just enough information to be able to do further investigation when I have time and there’s a need. This is not a book for the HTML novice. They expect you to understand HTML/XHTML and CSS.
HTML 5 is a great improvement in many respects with what came before (though I must say the decision not to make it XHTML and to have lax syntax rules is probably a bad one in the long-run, but I understand the desires for compatibility. I just think that it’s going to lead to problems down the road). There are huge improvements in the ability to mark-up a document and indicate what individual parts of the document mean which will allow tools to scan documents and use them in other ways.
Besides those structural improvements, we have new ways to create real web applications using things like a canvas to draw, the geolocation API for positioning, drag-and-drop mechanics, integrated support for rich media (like audio and video) and several other useful features.
This book doesn’t go into details on all of these, but provides you just enough to give you an idea of how they work and how you might use them. Diving into the nitty-gritty is left up to you but after reading this book, you should know where to start.