I don't think the other reviewer here even worked through the book--if 'W' even read it--but as one who has, I have to unfortunately give the book low marks.(actually 2.5 stars)
First, I'll start with the good:
The authors introduce a lot of tools that help development very early on, and I appreciate their teaching style. I think they had the ability to produce something wonderful.
Now the bad:
Typos in Math and Programming books range from easily corrected to inexcusable. This book includes the gamut. (The publisher's site has no errata listed; I contacted one of the authors but never heard back) The first place I noticed errors that brought hours of frustration is on page 48. The authors incorrectly identify a few of Facebook's Mock AJAX functions as:
clickwriteform
clickwriteid
clickwriteurl
Then they proceed to use those incorrect functions in their code. I found their error by consulting Facebook's API and seeing that the correct functions are clickrewriteform, etc. (notice the 're' in the middle--it's easy to miss. And apparently they missed it a lot in the book.).
The next place that shows extremely poor editing (do these publisher's editors get paid for this work?) is on page 79:
"Our file (let's call it auto_update.php) starts off the same as appinitiate.php"
There is no 'appinitiate.php' ever mentioned in the book to that point. The authors meant 'appinclude.php'. But this mistake is forgivable except for the fact that the reader is given code to update user profiles, but never told just how this 'auto_update.php' file is ever called. And the code that accompanies the book (via a download from the publisher's site) doesn't include any of these lines anywhere. So, One has no idea just how this php code will ever get called. Instead, after presenting the different lines of code:
"...
Now, we need to set the Facebook user manually:
$user = '614902533';
$facebook->set_user($user, $appsession);

Finally, we can send some text to the profile:

$fbml_text .= "You've been tagged!";
$facebook->api_client->profile_setFBML($fbml_text,$user);

Then, it's just a matter of logging back onto Facebook and seeing what affect we've had:"
As I mentioned: just how is this code ever having any effect on a Facebook profile? (It doesn't, btw. Here's why: the session *is* tied to the person logged in--and it changes when someone logs out. The authors incorrectly state that the session isn't based on logins, but rather on the install of the app. So, if one logs out as the authors instruct, the session ID you use to alter your profile will no longer be valid. The only way it works is if you're logged in and if you visit the php file on your server directly. This means this entire section of the book is invalid and sets readers up for failure.)
I have the impression that the authors rushed it out and the editors didn't care enough to have anyone test the quality or accuracy of the book. Frankly, I think it's generous to give this book 2.5 stars.
One can blame the publisher for poor editing, but one can also blame the authors for not supporting their work (by at least setting up a forum to let readers help each other, or to have the publisher do this).
p.s. I'll update this review if I finish the book so I can reinforce it's strengths or weaknesses. I might just drop it and use the online API docs.