While I personally really enjoy Doom and Quake, I am not much of an ID software fan, but the book still gripped me hard. You might have heard lore, legends and trivia regarding the duo and their games, but there's even more to be found in here, thanks to the countless interviews with first hand witnesses the author based his work upon.
Masters of Doom was released in 2003 which unfortunately means it's fairly up to date on what the two Johns have been up to this decade. The 200X's weren't very eventful or notable for either of them.