It's good for a while, but gets kind of old... If you find it for $15 or less, go ahead. Otherwise, no.
Children of Mana is a game where you go around different levels and use a sword, hammer, bow or flail to find the Gleamdrop from beating enemies, inside pots, etc., and bring it to the gleamwell, bringing you to the next room, eventually bringing you to the boss. You go through the cutscenes (which can be skipped), then you fight a fairly easy boss. You go back to Illusia then. That's pretty much like a home base, like Treasure town from Pokemon Mystery Dungeon: Explorers of Sky, or Beanbean castle town in Mario and Luigi: Superstar Saga, or Clock town in The Legend of Zelda: Majora's Mask. You can return to Illusia at any time, where you can complete quests like those in the Pokemon Ranger series, change the gems in your Gem Frame that affect your stats and grant you strange abilities, change the Spirit that assists you in levels, or buy and sell equipment and healing items.
Graphics: 7
Music: 7
Story: 5.5
Gameplay: 5.5
Length: 4.5
Difficulty: 5
Sound quality: 8
In total, it's about a 6 out of 10. Buy it cheap or don't buy it at all.