The format is a mass-market paperback, but this isn't a novelization but rather the screenplay as the movie was made. You'll notice that last has a subtle distinction. Oftentimes screenplays differ notably from the movies as you see them--scenes are cut because they didn't work, cost too much to do, or just because of the limits of time. The screenplays of Brazil and Monty Python and the Holy Grail are full of wonderful little tidbits that didn't make it to the screen. Unfortunately, for Life of Brian, there's only the parts that did get made, which are funny indeed, but you've already seen them.