The first chapter is a bit odd and basically reads as a CV with a bit of family history chucked in for good measure. Really, was this necessary? Shouldn't he let the marketing department of his publisher do this? He then tells of his father's high status as a theologian and his subsequent denial of his father's faith at the age of 15.
The following chapters tell of his old defence of atheism and a rather poor defence it is. I must say that Hitchens, Dawkins, Harris, Loftus et al can do much better. All too often an atheist will cede too much ground to a theist because there are so many theists and can they all be wrong? (Can 1 billion Chinese people be wrong about rice being better than chips?) Much ground is also ceded because theists seem so sincere in their beliefs.
The following chapters then say why he has changed his mind and he now believes in God because of the insuperable problems of: the fine tuning in the physical laws of the universe; the problems of spontaneous chemical bonds eventually, after eons, giving rise to life; why there is something rather than nothing - or, any laws at all to be fine tuned. On the plus side, he doesn't bang on about our difficulty explaining consciousness like other theists do.
He was shy to give himself a new label to replace the old atheist label. He states that he has not had a transcendental or personal meeting with the God of any religion but this is just a merely logical outcome of the facts as he sees them. Of course his new label is Deist which means belief in a God that does not meddle with human affairs and has not revealed himself to humans. People rashly describe him as a theist (someone who believes in the God of a particular religion). However you take this book you must still agree that he's still an atheist in regard to the Christian, Islamic, Jewish, Mormon and Hindu Gods and gods.
Flew's about turn has indeed caused ripples throughout the atheistic universe and theists have jumped on this. Of course, they don't mention the number of high profile Christian apologists (John W. Loftus being one) who are now atheists based on the evidence.
I admire his Socratic oath: to go no matter where the evidence leads. But his new found worldview is not self-questioned. When Flew engages Swinburne's idea of a non-corporeal, non-created, pure consciousness he could only think to say, "That sounds very strange to me". He didn't try to see where the evidence leads him. I too like to follow where the evidence leads me. Flew used the tired mind boggling probability of a monkey typing a legible sentence on a typewriter to indicate how improbable spontaneous abiogenesis really is. Let's forget that monkeys typing is a rather poor analogy for the probability of chemicals finding bonds for each other. When we look close at the nature of God we too can see equally high probabilities for listening to and answering prayers. God must be scanning every 100 billion neurons of every 6 billion people on the planet on a second-by-second rate. Now, to answer the prayers that he finds he must answer them in such a way to stop mutually exclusive events from occurring and other events from non-occurring that would negatively affect the desired outcome. If we take a simple matrix of three people and one has a prayer that God wants to answer and there are 20 possible steps to it being answered and at each step each person could make 3 possible choices then the number of possible outcomes to lead to the prayer being answered is: 3 (choices) to the power of 20 = 31,381,059,609. Then to factor in the three people in our matrix = 31,381,059,609 to the power of 3 which results in a number 32 digits long. When we factor that this is one matrix upon a possible 1 billion Christians then we see how improbable God is. But Christians maintain he is simple and uncaused (to get around the infinite regress problem) and that he acts outside of time (to get around other problems - mainly the one that I mentioned). One can quite clearly see that Santa Claus is a much more plausible entity in which to believe.
Flew should follow his Socratic oath and become agnostic, if he's intellectually honest he must realise that the notion of God (both the deistic and theistic notions) have many, many insuperable problems.
I believe he loses all credibility when near the end (of the book) he spends just a few paragraphs of open questions as to whether God has revealed himself to humans. He says that Christianity is the revealed religion to beat because it has a noble and charismatic figurehead in Jesus and a first class intellectual in St. Paul. Oh really, Jesus actually needed help from the devil in order to sacrifice himself (Luke 22:3) and St. Paul really did believe that madness is caused by demon possession (as did Jesus).