A good deal of the book's material is clearly based on experiences that Varghese could not have know about unless he heard it from Flew. Varghese was how old when the Lewis-Anscombe debate took place? Was he even born?
We have to distinguish first of all between criticisms of Varghese and criticisms of anyone else. It seems like a lot of people are getting tarred with this brush. There are accusations almost at evangelical Christians as a whole which are disturbing to me. Is Habermas' longtime friendship and discussion with Flew after their debate ghoulish? I was even called giddy by someone.
I'm not giddy about Flew. Since I am a theist, I am pleased that he has discovered that theism in some form is true. It is also commendable that Flew is willing to re-examine long-defended positions. I would be glad to know the story of his journey. But I'm not sure we can expect him to be a leading spokesperson for the arguments he accepts and to engage the philosophical debate on those arguments. I can understand Flew's coming intuitively to accept certain arguments without necessarily being able to be the "point man" on those arguments. If I am right, the arguments he provides are those also defended by people like Robin Collins and Richard Swinburne, and it would be worth hearing from them to see if Flew has competent versions of those arguments. I would know, for example, if Flew were to have an AFR section in his book, whether it made a real contribution to the discussion or not. A charge of incompetence from a dismissive opponent doesn't do much for me.
Most atheists today don't defend atheism the way Flew did. The nonsense charge and the logical problem of evil have been supplanted in the literature by other arguments.
"This is really Roy's doing." A lot is going to depend on the antecedent of "this." Is it the book's content as a whole, or its being put together. If Flew provides the content, Varghese writes it up, and Flew reads it 10 freaking times to make sure that it really does reflect what he believes, and it is marketed as a co-authored work, I don't see that this is fraudulent. I don't understand the "ghoulishness" charge, but I think the real issue is a charge of fraud.
Everyone agrees that some impairment is at work in Flew. The question is whether that impairment has affected his ability to understand and defend philosophical arguments, or is it just trouble remembering names. Or something in between. Medical professionals don't use the term "senility" anymore. Not everything collapses at once and in the same way. Mental abilities are lost in pieces, and short-term memory goes first. Alzheimer's produces a general intellectual collapse, but I see no good reason to believe that Flew has Alzheimer's.
People look at it and say "Oh, same old theist stuff" but that "same old theist stuff" is being debated in the philosophy of religion.
The fact that Flew isn't inclined to enter into pitched debate with the Richard Carriers of the world does not mean that he doesn't hold his convictions for intellectual reasons. (In particular his unwillingness to get into a point-for-point debate with Carrier is, uh er, kind of understandable). It does mean that we should not look to him as the "point man" for the relevant arguments. The fact that you, as an atheist, think poorly of these arguments does not prove fraud.
Has Flew been diagnosed with Alzheimer's disease? If yes, then I would say this is fraud. If no, then we still do get a glimpse of the mind of Tony Flew.
So I say: Christians, don't overestimate the apologetic value of Flew's conversion. Arguments have to be assessed on their merits. The book may be an account of an interesting intellectual journey but may have limited value as apologetics. Atheists, don't accuse people of fraud unless you really do have good evidence for fraud. So far, I'd have to say with Bertrand Russell, "not enough evidence, guys, not enough evidence."