This book just keeps getting thicker and thicker with each release! Now it's a hefty textbook size. The quality of the paper and colors in the book is quite good. As far as the information contained within, it's in the same vein as the previous versions. I have the 2nd version only, so compared to that, it's similar, if not better organized. The authors have expanded on the first few chapters of the book, regarding the history, and care of maples, but it's basically just added information to the previous text (a lot of it is verbatim from the earlier edition). I like how the cultivars are now organized simply by name. I'm not sure if this was something done in the 3rd ed, but in the 2nd, the cultivars were broken down into leaf shape, and then alphabetical. This was more difficult for me, and really served no purpose (in my opinion). The layout now makes more sense. The information for each cultivar is similar to previous editions. A couple of paragraphs with factual information regarding leaf type, shape, sun/shade requirements, etc. And of course, it includes a lot more than previous editions, as new cultivars are introduced.
The book does have a few drawbacks though. My biggest gripe is with some of the photos. Though most are beautiful and accurate glossy photos, some are way overly photoshopped. Many people will make their maple selections based on what they think the leaves will look like, and some of the photos are so over the top, the reader will surely be disappointed when they see their maple in reality does not show the brilliant coloration as in the photo. One example is the photo of Ap Crimson Queen. You will clearly see the color "dial" in photoshop was turned to maximum, as the colors just simply look too saturated. There are plenty of other photos in the book which do not reflect the true nature of the plant illustrated. Comparing to my own collection, it is clear some of the book's photos have been tweaked to bring out aspects of the leaf which may not normally be so striking.
Another nit-picky problem I have is with some of the name changes. Though perhaps scientifically and technically correct, changing some of the names around just makes it confusing. I have known "Ap Aka Shigitatsusawa" to be Aka Shigitatsusawa for a long time, and that is the way most nurserys (online and physical) call it. But the author made a specific point to rename this selection Ap Beni Shigitatsusawa. It may be technically correct, but trying to find the former in the book leads to a dead end. There are other examples of this, and it's nit-picky I know...but perhaps they could have better led the reader to the new, corrected entry.
Overall, this is a nice, high quality book with good information. Though some of the photos could be more realistic, most are fine and only add to the information. It's one of the best quick reference books and makes a nice coffee table book. If you are a Japanese maple enthusiast, you'll find this book to be very good and full of good information.