This book is very well written, complete, clear. It includes a first part about how to use the Eclipse IDE (you could find that out from the Help in Eclipse, but this is much clearer and structured), and a second part about writing your own plug ins. There are plenty of examples, and some very useful exercises. If you've never worked with Eclipse, this is the book for you. If you already used it a bit, I'll bet you'll find plenty of new tricks and features explained here that you had never seen or understood before.