A fun RPG that covers everything, including drawbacks.
The battle system is sluggish and takes a while to get used to, especially if you're not used to it. However, once you figure out how to time everything with the animations, it's fun and rewarding. I would have enjoyed being able to control a character other than Cress, but that takes nothing away from battles. Although, it would help if Mint wasn't so preoccupied with casting Dark Mist every other spell, even after learning more advanced healing and stat-boosting spells.
Battling takes some getting used to, but once you do, it's fun.
The graphics are some of the best I've seen on the GBA. The character sprites look good, and are easily identifiable. For example, in towns and dungeons, you can easily tell many of the NPCs apart. Battle sprites are detailed for both your characters and for enemies. Wolves actually look like wolves, you can tell the difference between Ocrots and Treants, and Dhaos looks, in my opinion, better than he does in Kosuke Fujishima's concept art.
Now, on to sound. The music sounds amazing for a handheld. Although it's still made largely of handheld-type sounds, the music sounds like music. It does exactly what game music is supposed to do: add greatly to the experience of the game. I personally think that the music does that very well. The voice acting, on the other hand... while it is easily distinguishable as words instead of the mumbling that you'd expect from a handheld, character lines are cheesy and annoying. Personally, I'm sick of hearing Cress yell "I did it!" or Arche yell "I won! I won!" at the end of every battle. Maybe it would be better if the characters had more than one possible after-battle line.
The characters are largely stereotypical, but they don't fail to be interesting. Cress is a typical RPG hero- not too bright, strong sense of justice, acts on impulse. Mint is pretty normal too, as she is soft-spoken but will greatly stand against injustice. Claus is amusing, he usually has a cool head until someone mentions the idea of humans using magic, then he gets almost as excited as Symphonia's Raine when she comes near a ruin. Arche is the loud one, who seems to be jealous of Cress's relationship with Mint. Chester speaks his mind, seemingly without thinking. Dhaos is a traditional RPG villain- strong, intelligent, and not as evil as everyone thinks him to be, the type of villain that you don't want to have to kill in the end. Phantasia doesn't have as much character development as it does plot development, but the characters are still interesting and add to the experience as a whole.
The plot is deep, but still easy to follow. It spans 3 time periods and has you running around quite a bit (during the part that takes place in the past, you often are forced into unnecessary gald spending in order to cross the water). It has its share of twists, secrets, and revelations, and does what you expect an RPG plot to do- draw you in and keep you on the edge of your seat, like a good book.
I have never played the original SNES version, so I'm not sure what has been gained or lost from the GBA port. Mostly, I bought this game because I enjoyed Tales of Symphonia and was hoping for a similar experience. Although Phantasia has its drawbacks, I greatly enjoyed it. In my opinion, it's one of the best things ever programmed into a GBA cartridge.