Aleister Crowley is certainly in need of an objective biography, and this book almost delivers.
The author's strong points are his knowledge of esoteric societies and ideologies, and thanks to his access to Crowley's papers, he has been able to tell the tale as Crowley experienced it. I like the way Churton doesn't try to tell the reader what 'really' took place in the frequent supernatural incidents. He describes what happened, how Crowley experienced it and what was the context, and lets the reader decide.
But the book has its flaws, some merely irritating, others really serious. Churton doesn't quite worship Crowley, but comes close. Therefore he often attributes to him prophetic abilities that are very much overblown. You didn't have to be a prophet in the early years of the 20th century to see that a great war was coming or that Russia was on verge of revolution. But Churton, in awe of his subject, sees these as examples of Crowley's powers. Also I'm not at all certain that Crowley's intelligence role during the WWI was as important as the author makes out. For example, Crowley could not have influenced the supposed German decision to sink Lusitania for the very simple reason that such decision was never made by German leadership -- the decision was made by the U-boat captain on the spot.
For reasons already mentioned it's obvious that the author's grasp of political history is weak. He's so intent to prove that Crowley was continuously involved with the British intelligence agencies, that he seizes quite minor and circumstantial incidents as evidence that Crowley was employed as a secret agent. The most blatant example - and the book's worst blunder - comes on page 293. There Churton describes a military crisis that allegedly took place between the UK and France in 1926 over Egypt's western border. I found that very remarkable, because (for example) France didn't have any colonies bordering Egypt (its western neighbor was Libya, an Italian colony). I made a Google search ("The East African Accords" using the citation marks), and what did I find? Only one website describes such a crisis - an alternate history website! If only Mr Churton had bothered to check the front page, he could have seen that for himself.
As far as Crowley's life and the doings of a small coterie of occultists go, this is a worthy book, and makes sense of why Aleister Crowley became such a counter-culture icon. Churton expertly dispels the old calumnies about Crowley as a Satanic corruptor of maidens and youth. But whenever the author tries to make a point about the world surrounding them, you better remain very skeptical.
