After becoming so excited about Planet Narnia, I couldn't resist ordering these two biographies of CS Lewis from trusty Brotherhood Books -- I had no way of knowing which would be superior so I bought them both. (There has to be some disadvantage to ordering online, and the inability to leaf through and sample the text is definitely a disadvantage.)
However, it was a very interesting exercise to read the two books side by side and I don't regret my double purchase. CS Lewis: A Biography by AN Wilson was published in 1990. It's a dense, scholarly work, somewhat dismissive of the Narnia books, which Wilson claims are 'poorly written', albeit in the throes of 'white hot' emotion. Wilson places more value on Lewis's academic work and his religious apologia. He is clear-eyed and unsentimental about Lewis's complicated private life, and his personal weaknesses, and is disdainful about the body of work (which I was unaware of) by hard-core Christian fans which seeks to paint Lewis as some kind of saint.
Michael White is similarly scornful about the blinkered sanctification of Lewis. But his biography, CS Lewis: Creator of Narnia, published in 2005, is written from the viewpoint of an unashamed Narnia fan. White has had an interesting life himself, including a stint in the Thompson Twins (!), lecturing in science at Oxford, and writing on science for GQ. He gives Lewis's fantasy writings pride of place, the central chapter of his book, and while he covers much of the same ground as Wilson, his book is organised by theme rather than strict chronology, which can be a little confusing. White's book is lighter, shorter and perhaps marginally more readable than Wilson's, and the positive attitude to the Narnia series is refreshing; however, Wilson's is probably more informative.
Needless to say, neither writer has picked up on the 'planets' theory. But I certainly know more about Jack Lewis the man and writer than I ever knew before.