Deborah Harkness' book is remarkable among scholarly works on Dee in that the entire text is dedicated to an in-depth analysis of his angelic conversations. She has brought a powerful voice to Renaissance scholarship with methodological insight into how to study Dee's place in the wider cultural "conversations" of his time. Up to date on the difficult issues surrounding the interpretation of the place of alchemy and cabala in Dee's work, she provides a compelling argument in support of the sophistication of both his scientific and theological learning.
Harkness has also made a solid contribution with her research into Dee's sources on angel magic, offering the reader tantalizing glimpses into Dee's marginalia in texts like the dionysian corpus (see her longer PhD dissertation for more juicy text gossip) and other neoplatonic texts, without falling into the trap of blindly following the opinions of past scholars either positive (F. Yates) or negative (K. Thomas).
This book is dense but readable and offers and excellent place to start in the intimidating world of John Dee studies. As a student transitioning from undergrad to graduate work I found it most helpful, and a ready jumping-off point for more. The bibliography is rich but not unwieldy.
If you're interested in the "Dee and Renaissance Talk" angle a good place to go next is Sherman's book on Dee and the Politics of Speaking and Writing. If the "Dee and Renaissance Magic" topic is more to your liking seek out Szonyi's book on Dee's Occultism. For language/theory check out Hakansson's "Seeing the Word." If you just want to know about Dee's place in the history of science read Clulee. To get up to date on the cutting edge of Dee scholarship see Clucas' interdisciplinary volume. For Alchemical information see the recent Dee-centered issue of the Ambix journal.
Google Claire Fanger's excellent review for a more academic point of view than mine.
No bookshelf or library on Dee, or Renaissance Magic in general, could be complete without this book, and will be well-used by those with curiosity and a demand for efficient management of information.
