Obviously, being a Game Boy game, it's hard to judge the quality of this game. It's a Final Fantasy game, to be sure, but it definitely doesn't follow the usual conventions of one. For one thing, when you buy weapons from the shops, you're essentially paying for a limited number of uses for that weapon. If you buy a long sword, for example, you'll be able to use it 50 times before it runs out. The same goes with spells, even, as almost any character can buy spellbooks with a set number of uses.
One thing that I liked was the way that the different races played. Humans pretty much had no natural abilities, but could be beefed up with the different items that you buy. Mutants (my personal favorite) could develop their own skills and spells, but also immunities and weaknesses. Monsters eat the meat of defeated enemies and change into different types of monsters (either weaker or stronger). Robots pretty much got weaker or stronger with the equipment you gave it. Giving your robot strong weapons and armor would boost its stats and HPs as well.
There's hardly any story to care about, so it's mostly about your own characters developing. One thing I found annoying (but unavoidable due to the nature of the race) was that my mutant could have some awesome spell and immunities, but randomly, he might lose it and become much weaker. Sure, you could reset and not save, but the whole thing could get annoying. One thing I liked to play with was my monster. Basically, if you followed the right steps in eating meat from certain kinds of enemies, you could make it very strong. In fact, you could have a monster that's far too powerful for the world you're currently in, so this added a nice little twist.
All in all, it's a unique Final Fantasy game with little or no story. But the way they approached character development was interesting and clever.