Levy had unprecedented access to top level executives for this book. This meant that you got all the details about Google's funding, it's approach to top secret projects (including the Android acquisition as well as Book search), and what really happened with the Analytics acquisition. Well, not quite. You could take Levy's book at face value, but it's peppered with all sorts of little inaccuracies that point to the fact that Levy was painted a very nice picture, and as an outsider and not someone who lives Silicon Valley culture, the most he could do was to be a little bit skeptical about it.
For instance, there's a little bit about how Google Docs killed Gdrive in a brilliant play of executive politics. But Levy leaves out the context: Dropbox has made a billion dollar business out of that lack of vision by the Google executive. Then there's minor little details like a remark about Jia being famous for Sushi. Uh, no. The big sushi cafes at Google at the time were Pacific and 5IVE. It's very clear that Levy regurgitated whatever line he was fed very well and entertainingly, but obviously his fact-checking was limited or he's clearly preserving future access to Google executives by being as uncritical as possible. The only place in the book where he takes a skeptical look at Google's actions was in relation to China. Even then, there's careful avoidance of the internal craziness at that time (seriously, "blame the intern" didn't go over well with the rank and file at that time, and sticking to that line is definitely something Google's executives should hang their heads in shame about).
On the other hand, there's plenty to like about this book. There are places where he foreshadows the tension between Schmidt and the founders. There's an excellent exposition of Eric Veach's re-invention of the Vickrey auction, and the sun-setting of early versions of Adwords (known at the time as Adwords Premium). There's even a somewhat extensive coda about Google's failure to copy and the consequences thereof.
If you're an old Google hand, you'll get a few kicks out of all the names mentioned in this book that you're familiar with. If you're not familiar at all with Google's story, this is a great book and is recommended. After all, if you wait for a definitive account, you could be waiting a long time.