I am half way through volume 2 of the two volume set of Edible Forest Gardens books by Dave Jacke..wow...what a lot of words !
These are the most wordy books I have ever read, but some good information. Most of the information I was already aware of and it is quite a lot of words to read to get through the information, could have used a bit of editing in my humble opinion.
However, I do recommend reading it as there is some good information in the books that I haven't found in any other books that I have read (and I have read an extensive number of gardening books).
I also would recommend that you first get the books from the library and read them before you decide whether or not it is worth your $150 for the set, for me it wasn't but for those with more money it might well be.
I would recommend if you can't get it at a library to read or afford to purchase it you stick with Gaia's Garden by Toby Hemenway which has a lot of the same material in a less wordy and easier to read single volume.