Head First HTML5 is a good book on HTML5, and by the end you will have a good familiarity with HTML5’s core components.
The example projects worked through in the book are good and relevant. For example Chapter Five introduces location awareness and uses Google’s geolocation tools to show the location of your device and later even maps it using Google Maps.
As with other Head First books I have read, I didn’t have any problem reading this book cover-to-cover easily. I can recommend this book for learning many aspects of HTML5, but you’ll have to get your CSS introduction/refresher elsewhere.