Besides being incredibly inventive, making the specific choice to use Death as the narrator in The Book Thief allows for the novel to unconventionally take the readers through the story (and back again). Using Death to narrate means that the story's plot can move in a non-linear fashion, can change setting...
Besides being incredibly inventive, making the specific choice to use Death as the narrator in The Book Thief allows for the novel to unconventionally take the readers through the story (and back again). Using Death to narrate means that the story's plot can move in a non-linear fashion, can change setting spontaneously, and can provide intimate details about characters that only an omniscient narrator can.
Death informs readers early on that many of the characters die; as Death, the narrator reminds us that life inevitably comes to an end, but the effect of each character's death leaves such an impact on him that he must carefully tell their story. While initially spoiling the ending is thought of as disappointing, as readers work through the novel they begin to think like the narrator to understand why Liesel's, Rudy's, Hans', Rosa's, etc., journeys are so important to share. Since readers already "know" the fate of the characters, having a traditional plot line is not as important; as Death moves about from place to place and through time collecting souls, Death therefore becomes the best mouthpiece to tell the story in this nonlinear way.
Because Death is a named omniscient narrator (as opposed to an unknown omniscient narrator), we know that Death must travel the world to find people at the end of their lives–this sets up Death's ability to change the setting of the story through space and time to connect the lives of Liesel's and Max's. Death can come back to the same point in time (e.g., hint at the character's death at the end of the story) and can shift from location to location (e.g., move from Himmel Street with Liesel and the Hubermanns to Max on the run).
One last pro about using Death as a narrator is that Death can peek into the minds and actions of the characters; in this way, Death can seem detached from the action as if Death is zoomed out in a camera but also speak as if Death is in the mind of a character. Readers are therefore able to "see" the scenes from many perspectives or from only one. Because Death is not human, Death can also create a distinct relationship from the reader, as one "haunted by humans" Death can take the time to marvel at the oddities of human life, yet simultaneously seem understanding as Death has seen it all.