Answer

Generally speaking, I would say that Leibowitz usually bases himself on a correct argument or a correct point, and then takes it one step too far. For example, he says that prayer is an obligation of recitation, like an obligation to recite a telephone book. Here he takes a correct point—that prayer is a commandment like any other commandment, for which one must intend to fulfill one’s obligation—and ignores its other aspects.
There is nothing that is simply good or bad to adopt. Every argument or claim has to be examined on its own merits. It’s hard for me to write an essay here about Leibowitz. If you have a specific question, please raise it.