The conclusion to the Digital Devil Saga 2 is here, and it's better thent he original, for the most part.
Unlike many multiple-part console RPGs (such as Xenosaga or .hack) jumping in without playing DDS 1 isn't too confusing. The storylines are almost completely seperate, most of the loose ends from DDS 1 being tied up during the first couple of hours of gameplay; relevant info for those who haven't played DDS 1 is conveyed through (brief) flashback scenes. Those who jump in at DDS 2 probably won't understand things quite so well as those who have played DDS 1, but they will be able to figure things out without being too confused.
In terms of gameplay, everything that was good about DDS 1 is here and improved, nothing has been removed. DDS 2 still uses the turn-based from DDS 1; where hiting weaknesses or scoring criticals can give you extra turns while hitting an missing or hitting an enemy's strength can reduce the number of turns you get or even end the round for the party entirely.
Ailments have gotten some additional effects, most notably, attacks that share the same base as the ailment will be more effective when targeting those effected by the ailment. In other words, if a character is cursed and is targeted by a death-based attack (curse being the death-based ailment) then death-based attacks will be more effective. Other effects include sleeping returning HPs and MPs to those effected by it, and confusion now occasionally making a character toss away money.
The most vaunted addition, beserk mode is the most interesting addition. When solar noise is high, there's a chance you'll begin a battle in a half-demon form called beserk mode. In beserk mode, you can only attack physically, meaning no MP draining attacks or using items, but these attacks go through any physical shields the enemy may have. In beserk mode you are also more likely to critical and do more damage, but also take a lot of damage if hit in return and take criticals; even more then when in human form. In return, winning a beserk mode battle earns you more karma and atma however, which makes it worth the risk. Beserk mode is basically an all or nothing proposition, where you either win the battle and get tons of karma and atma or you wind up (if you're lucky) retreating from battle severly damage.
Human form has also become more powerful, guns dealing out more damage then before. In addition, you can now also catch some of your enemies in human form, and in human form (both you and your enemies) have a weakness to gunfire.
The graphics seem slightly sharper, but more importantly, there is more graphical variety. Not everyone is in some sort of gray armor suit, and the environments tend to be a bit more varied then DDS 1, which only had a couple of dungeons that were significantly different in graphical style. In DDS 2 you'll see a range from an underground urban decay style city, to utopian office space, to dungeons that appear to have been thought up while on acid.
Compared to DDS 1, the sound is noticeably different but overall was worth about the same. While there weren't any glaring problems like in DDS 1 (such as Sera's singing) there weren't any music pieces that really grabbed me like in DDS 1. The music in DDS 2 is more varied then DDS 1, which was primarily made up of electric guitar with some orchestral bits thrown in for good measure; DDS 2 has more of a range of music, with the music for the underground city being noticeably different in style then that of the dome city or the later dungeons.
Finally, Digital Devil Saga 2 is a few hours shorter then Digital Devil Saga 1. I completed the main storyline without defeating any side bosses in roughly 30 hours for DDS 1, while I defeated four (relatively weak) side bosses and went through the main storyline in roughly 25 hours for DDS 2; though it is worth noting that if I hadn't fought those four side bosses I probably would have needed to wander about and level up to complete the game.
Digital Devil Saga 2 fulfills much of the promise shown in Digital Devil Saga 1, though some small quirks keep me from stating that it's everything I hoped for. If you picked up DDS 1 and enjoyed it then pick up DDS 2, you won't be disappointed. If you're looking for a highly original RPG that's far off the beaten path then I fully recommend DDS 2, just keep in mind it's tough, just like it's predecessor.