Having recently sat an ITEC exam, the bad news is... you need to learn this book inside out. The really bad news is that its a lazy book which is full of errors, and even worse proof-reading. She can't even agree with herself in different parts of the same book.
The good points about this book is that the info is very clear. They are in common name order, rather than latin which is helpful when you are learning. As long as you can verify the info which another reference book, you'll be ok.
Just watch out for the sloppiness, any lecturer worth their salt will be able to point out the mistakes.
Buy the book if you are taking an ITEC exam, and learn it, but always bear in mind that other books are better