A 9/10 alongside The Dark Knight. Was one of the films that made me interested in the screenplay aspects of movies.
Reading the screenplay of the Nolans and comparing that to both professional and amateur screenplays, makes me appreciate the use of space on a page. Despite their scripts being generally on the long side, you tend to find little wasted scenes or dialogue. Everything is deliberate and The Prestige is a fantastic example of that. Every scene presents a mystery or clue and adds so much to the replay value.
Never get enough of this one.