Great fun, but a tad frustrating at times.
Positives:
This game has an excellent job system, effectively known as "crowns". If you played FFIII for the DS, you saw that you had a level and a job level. In this game, you just have a physical level and you can change jobs at will without taking a stat hit. However, you can "level up" the jobs but putting jewels in the crowns, which grants powerful and necessary abilities.
Another excellent thing this game does is it did away with MP. Now, you have ability points that appear in the form of 5 "bubbles". You regain one bubble automatically at the end of each turn, and you regain multiple bubbles if you sacrifice a turn to do so. A basic attack takes one bubble, Cure takes one, Cura, takes two, etc. Your class also has an effect on how many bubbles a spell takes, for example a White Mage only needs to spend one bubble on Cure while other classes may need to spend two.
Drawbacks:
Simply put, this game can be tough at times. Not a "fun" tough, but the time where you will need a walkthrough because you won't know what to do or who to talk to, or you'll need to backtrack through an entire dungeon after defeating a boss. Stuff like that, that could have easily been avoided.
This game is definitely worth a purchase for RPG fans and DS owners, however.