What tone does McCourt use as he characterizes the conditions of his youth when he writes, "It was, of course, a miserable childhood: the happy childhood is hardly worth your while"?

McCourt's tone here is in keeping with much of the rest of the book in that it is blackly comic—this quote is not intended to be interpreted seriously. McCourt's sardonic tone invites the audience to infer that the writer's experiences led him to believe that most childhoods were unhappy, and that this belief was reinforced by the idea that being unhappy was simply a way of life; having a happy childhood would have been, somehow, an indulgence, or a waste of time. Note the use of the phrase "of course," and the colon, which seems to imply that he is repeating an overheard or learned idea. He does not comment on this idea, but his tone suggests that he does not agree with it, and nor does he expect the reader to. He is making a joke of his own past, but the misery was surely real.