I think that when you have a debate with someone, you want to find some common ground and at least have some first principles in place. When that other person is so insistent on beating you that they even begin disputing things that seem irrelevant and are largely settled, it really sours the atmosphere. That's how I feel reading Carlton. He also has a bit of a problem as an outsider in that he zeroes in on things I would consider to be relatively minor or inessential parts of the RCC and makes a huge deal out of them.
I can understand your frustration with this book--I read it as an early inquirer and the whole time I felt like his statements on the Catholic Church were exaggerated, distorted from their actual meaning, or simply untrue. With feelings like that, Carlton made it easy for me to dismiss objections that might have actually been valid. I found Orthodoxy and Heterodoxy
by Fr. Andrew Damick to be a much more difficult read, because his objections couldn't be so easily disregarded. More difficult because of how it was affecting my Catholic identity, but much more worth reading, in my opinion.
I'm only now starting to read The Faith
after several people recommended it, but The Truth
really soured me to Clark Carlton.