First off, I'm no expert in the Kabbalah. I think it's important that I say this as this book may have many factual errors that I wouldn't detect because of my lack of expertise in the subject. As such, I'm not going to comment on the book's accuracy, only my experience of reading it, and how things appeared to me as I did so.
As the title implies, this is a simplified version of a very complex subject. If you find yourself intimidated by other books on the subject, this might be the place to go to clear up some of the basics.
It's an easy read, written in an approachable style, and is short enough that can be polished off in a single sitting.
I found this book fairly useful, but it's not the be-all end all of this subject, and while many of my questions were answered, I was left with plenty more.
This is pretty good for what it's trying to accomplish,I think, though I wish the author had gone for just a little bit more.