If you liked the originals, You'll love this game.
OK so to actually get into the review now.
First off is the game play. To say a single word about it, incredible. The control scheme is easy to use, also the ability to use the stylus to control where you want to go is great. For that and the ease of switching between screens during battle, and in the menu it to me is one of the better parts of the game.
The battles are just like the old games with better graphic and more summons. During the battles there are the same options as in the older games as well as the ability to change characters in the middle of a battle, just in case you need say a second wind adept or you need more physical power over psy-energy. I can't tell you how many times this little ability to change on the fly has helped me out. Especially when it comes to boss battles. Not that I am going to fill this review with spoilers. I'm just stating that during a boss battle its nice to have the ability to change on the fly.
The puzzles, ok we all know and love these games for the puzzles, this however is one part where this game lacked in the difficulty. In the first ones there were some puzzles that took me hours to get through. However in GS:DD they were lack luster and almost seemed rushed. For example about halfway through you need to get through a tall mountain and it seems hard at first but when you realize that one of your characters has the ability to practically tell you what and where to go next it makes the games less challenging and almost to easy. Don't get me wrong there are still some puzzles that give you problems mainly later in the game and right near the end of it. But overall the puzzles seemed to lose their over the top challenge factor.
The class system, now we all know that the first games had amazing classes when you combined certain djinn. Well it makes a huge return in GS:DD and when I say that I mean HUGE. With more Djinn than ever before and more combinations that ever before this game has been making leaps and bounds over the old ones. Im not going to go into too much detail as that would spoil this game for those of you that have not played but You will find the class that is best for you and your style of play. If you want High HP and Attack or High Defense and Psyenergy. Or even High HP and High Psyenergy. or any combination of the above listed. Also skills play a big factor in this game. And like before the type of djinn you have change what skills you learn as you level.
The leveling/EXP system. Ok in this game the exp gain system to me almost seems broke and to easy to figure out. At one point every battle a different character was gaining a level. My party has yet to be wiped out once and lose any money/items. Also with this it makes the game fast to run-through but when you get to the end it gets harder to get through if you don't level up early-on.
Overall if your looking for a fast-paced, fun, and all around great sequel to the first to GS games this is a great game to follow and continue the GS Legacy.
So in conclusion I'd give this game a Solid 9 out of 10 in my personal experience and opinion.