John Perkins This is the third book in an awesome series. I would recommend starting from the first book (Off to be the Wizard) as many of the character interactions make much more sense when you know the history. Plus, I think the first book is the best in the series.
Sherrie McCarthy I just read this book and it is the only one of the series I have read. I loved it and laughed out loud. But I doubt I will go back and read the first two now that I've read this one. (I wouldn't turn the book down, I just won't order it for myself). So yes it is possible as a stand alone, but then you may not want to read the rest!