Great game, itty bitty story.
The game has great atmosphere and sets the mood immediately with the opening movie. You get a very Matrix like feel to the world you are in and even the characters are Keanu Reeves-esque in the beginning. As the story unfolds, what little there is, the characters begin to show unique personality traits. It is very apparent form certain choices and tasks in the game that a sequel was already in the works when they made this game. But the story is the biggest drawback, because there really isn't one, you never get an explanation as to why you are the way you are or what is going on. Even beating the final boss is somewhat unsatisfactory since it doesn't resolve the story, it is more like an end to a chapter then a story.
The game mechanics are top notch. The battle system is similar to Nocturne and the Persona series, except you get to eat your enemies for extra Atma (the skill points). The Atma is used to learn mantra which give you skills and abilities for the game. The mantra grid does look intimidating at first as the price quickly soars for each successive mantra, but there is a new game plus mode that allows you to keep all learned mantra to the next cycle. ANother interesting aspect of the game is that certain choices and optional bosses will affect Digital Devil Saga 2.
Over all I gave this game an 8 because the story is just too thin. If you want to have a chance at mastering all the mantras for even one or two character you have to play for around 70-80 hours, this is not something I mind doing but could turn off other players who do not like to grind for hours at a time. This game is challenging but not impossible (unless you go for the optional bosses).