Sure, the content of this book is freely avaliable online, on valve's site no less, but that's not why I bought it and that's not why you're intrested in buying it. If you want a physical copy of the the Left 4 Dead comic 'The Sacrifice', The TF2 comics from WAR! through to 'Meet the Director' and Portal 2's 'Lab Rat' all in one collection, then you cannot go wrong with this book.
The presentation is immaculate. It's big (slightly bigger than a sheet of A4 paper), it's a hardback, and no expense has been spared in its production. The print is of the highest quality, the pages are thick, and the cover art is beautiful.
Basically this book isn't going to live in my bookshelf. It's going to live ON it. It's an artwork to display, with the feature that you can open it up and and be bowled over by the skill of Valve's artists in their ability to create such distinctive signature styles for each title. If you have any appreciation for the art created by the visionaries at Valve, or any intrest in comics whatsoever, you owe yourself this book (read: artwork).