What is it about Kafka's use of irony that makes it so unique?
This is a great question. If we take, Franz Kafka's work, Metamorphosis, as an example, we can make a few observations of Kafka's use of irony.
First, his use of irony is in your face. There is no mistaking it. In other words, it is so blatant that you would not imagine someone even attempting it. For example, Gregor is not like a bug; he is a bug. Moreover, throughout the work he acts like it.
Second, Kafka develops his irony in detail throughout his work. So, to use his work, Metamorphosis again, Gregor starts to feel comfortable as a bug. He starts to climb on the wall and hide under things. Even his family gets used to it. It is as if nothing out of the ordinary has taken place. Life moves on. In the end, we question whether Gregor ever really lived.