The book is 124 pages of Oracle/PHP goodness, covering a wide range of topics - all the way from introductory material on the extensions out to simple globalization within the data. It's not a complete or complex guide to all things Oracle, but it is definitely a great resource to get you up and running quickly. They also won't teach you SQL, so you'll probably want to have a background in databases already.
The book is free for all to download and use, so grab your copy [pdf] today!
Christopher Jones also notes that they have plans to keep it updated as new chnages in the Oracle/PHP relationship arise.