Assassin's Creed: Revelations - The Lost Archive reviews

Very good DLC for lore fans. It mainly touches on the subject of Subject 16. An account of Clay Kaczmarek's life and his time in Abstergo.
The DLC mainly consists of puzzles based on the use of the Animus. Unlike the main game, where the puzzles only serve as minor obstacles to the main storyline, here they form the core of the gameplay.