Colin Wilson died on the same day as Nelson Mandela. I've read a couple of appreciations of Wilson. This obituary from The Guardian provides a fair assessment. But while I agree for the most part with these assessments, I want to add a few words of my own.
I discovered Religion and the Outsider at a used bookshop in Berkley in 1997, when I was in the Bay Area for a deposition. I hadn't known of Wilson, but the title and a quick perusal convinced me to buy it. From that book (which I read not long thereafter), I went on to read The Outsider and some of the others in that cycle. I've also read his New Pathways in Psychology, which started as a biography of Abraham Maslow; however, it soon morphed into a history of modern philosophy and psychology as well as Maslow biography. I found some of this work quite intriguing. He seemed to have a sense of how existentialism works (or might work) other than by serving as a bleak outlook on life. Wilson developed his own theory of the brain and how it focuses on either the near-term or the long-term. He talked about how boredom can slip in when life has no challenge and no immediate goals. In some ways, he anticipates Csikszentmihalyi’s Flow and McGilchrist's theory of the two brains. Wilson culled his insight from a journey that went from a mundane car ride to a will-we-or-won't-we-make-it battle against inclement weather. The focus was all. This experience provided him with what he dubbed “the St. Neot margin”. In the focus and intensity the battle against the storm, he identified an antidote to the despair that marked so much of Continental existentialism. He seems more at home with the European thinkers than the English heritage of Locke and Hume through to analytic philosophy.
But Wilson was an autodidact, and this was both his strength and his weakness. He could roam into whatever subject his inquisitive mind desired, but he lacked focus and standards of proof to limit his conclusions. He delved into true crime, the occult, rogue gurus, biographies of fringe figures like Gurdjieff (whom, while fringe, is worthwhile), Jung, and contemporary magicians. He also wrote about Shaw and penned literary criticism. He often repeated himself and seemed undiscerning about evidence. He often concluded in favor of suspect occurrences and practices. He explored subjects with an eye toward his fundamental insight about human consciousness, which didn’t seem to have grown or deepened much. My reading of later Wilson doesn't show much deepening of his initial insights. This became the frustration of reading Wilson. Reinforcement is no doubt worthwhile, but one suspects that he spread himself too thin in writing about the fringe or the macabre.
Besides his insights into human consciousness, I appreciated his deep love of books. Wilson was a school dropout. So when he read, he read because he loved to read. Not assigned to read Shaw, Sartre, Camus, or any other author, he read with genuine enthusiasm. He shared this enthusiasm in his autobiography as a record of reading, The Books in My Life. This book serves as a form of autobiography and as a reflection on important works, such as those of Shaw, whom he admired.