This book is excellent. I wish many more books were like this one. I cannot express how much I enjoyed this book. There are just too many books out there that are just flashy, bulky, in-your-face, and just bloated with fluff. Not this book.
First of all, this book assumes that you know Java. That is rule 1 that many books fail to observe. This book is about wireless Java so it does not waste space teaching you Java. If you want to learn Java, you'll read a book that is written specifically for that - and you'll likely find a great one too. So why redo it in a way that will suffer anyway?
Second, this book gives you useful information, and only useful information. No space is wasted. Every chapter is concise, to the point, and specific. I've never read a book with such a high percentage of useful information. I'll gladly pay about the same price for a 200-page book with 190 useful pages instead of a 1000-page book with 90 useful pages. The presentation is clean, clear, and consistent.
Third, well, the topic is wireless Java, so I'll also tell you that I picked up this book knowing Java but not J2ME, and after reading it I know everything I need to know to writing Java programs using J2ME. I've looked at all the Java wireless books and I truly believe that this is the best one. You'll learn about how J2ME is partitioned, how MIDP fits into CLDC, what parts of J2SE are included and left out, how to write MIDlets and user interfaces, how to work with persistent storage (micro-databases), networking, performance optimization, XML, and security.
The author and his team (because a book does not come to exist by only one person) should be applauded for boldly going against the trend of selling books by weight.
One last note: this is the ONLY book for which I thought even the appendix was useful!
Enjoy it and enjoy trying out J2ME.