In addition to the lack of a clear organizing plan, Jeremiah is quite repetitive. The repetition is for emphasis, no doubt, and many very similar passages occur two and even three times.
The last chapter is unique because someone must have written it long after the rest of the book. The options are that Jeremiah or Baruch wrote it or that some other writer added it later. There is no way to tell for sure who wrote it or when, but it's purpose seems clear enough. It provides hope at the end of a record of discouraging circumstances.
The biographical and autobiographical sections of the book are also distinctive. No other prophet wrote as much about himself and his experiences as Jeremiah did, and no other prophet let us into his head and his heart as much as he did by sharing how he thought and felt.
Jeremiah used object lessons to communicate spiritual truth more than the other prophets. He made his prophecies concrete and vivid by this means. He did not delight to paint word pictures as much as Isaiah did, but he did acts and spoke of real situations far more than that earlier prophet did.
