The Digital Devil Saga series stays great, but loses some of its effect on the audiance.
The battle system in the game is still the same; your characters share a turn, and you can get more parts for the turn by exploiting weaknesses or getting criticals. They did change the Mantra Grid for this game, though. It is now a hexagon made of hundreds of other hexagons. You do not have to get a level on skill of an element to get the level 2 skill of the same element anymore; this gives you a little bit more customization for you characters. Sadly, it is not enough to remove the fact that all of the bosses require you to have specific skills to defeat them. Karma Rings are also added to the game to give them equipment. I enjoyed these because they are need for the increased difficulty of the game.
The storyline isn't as good as the first game's. It does answer all of your questions from the first game, but it also adds some unanswered areas to its own story. You also lose characters left and right as you progress through the game, and they don't come back until you are too far and their skills are too weak.
In conclusion, the game is good; it's just not as good as the first one. They made it so you would have to learn a skill to defeat one boss, and you won't need it anymore. The Mantra Grid is better and the added Karma Rings are a good touch. The storyline doesn't really leave you characters helpfull by the time you get them back.