I'm afraid I must start by saying I haven't read the English edition, but the Italian original. I approached it with high expectations, which were dashed.
Why did I find it disappointing? Perhaps I was expecting a bit more content; instead the book had the feel of a book thrown together to create a book. This is even more true of his companion volume, 'L'alfabeto ebreico'.
The illustrations seem too small to provide a useful guide to the caligrapher, and tend to concentrate - like to many books on Arabic calligraphy - on the illumination to the detriment of the calligraphy itself. The book also relies too heavily on Arabic typography, which isn't really the same as calligraphy, and which so often breaks the canons of calligraphy, with the result of seeming both ugly and hard to read.
I'd like to have know far more on the tradition of calligraphy and the calligraphers themselves; a more focused investigation of the styles used and how they've developed; a useful bibliography.
All in all, disappointing.