It was great back then, but don't expect to be blown away by an epic RPG experience.
While this "may" seem like a potentially interesting plot, the game executes this in such a poor manner that you may not even realize there was actually a storyline to begin with. Dialogue is incredibly limited and choppy, making the plot feel very much incomplete. An RPG that we see today may in fact contain more dialogue within a single cutscene than Final Fantasy Legend does in the entire game. This game is not plot heavy, or story driven at all, in comparison to RPGs we see today.
The gameplay is your standard turn-based RPG formula, with an exception of toned-down graphics and animation. The battle formula works pretty well, and while it isn't necessarily complex, it gets the job done. A downside in the battle format is the use of weapons. Most weapons will have a limited amount of uses before breaking. Usually, they range from between 30-50 hits before they can no longer be used. You can expect to have to buy new weapons for your party a few times before completing the game.
There are no "real" characters in Final Fantasy Legend. You give your main character a class (which ranges from Male/Female, Human/Mutant, and Monster), and a name. Using your main character, you can recruit new party members at a guild (all in which you choose the class and name). Each character is given an amount of "hearts." Each time a character is KO'd, they lose a heart. When all hearts are depleted, that character can no longer be used. Of course, you can always head back to the guild to recruit another member and replace that loss. From this format, it's easy to see that the storyline is not character-driven either. You will see no growth or develop any feelings towards any character in your party, like you may in a current-day RPG.
Graphics and sound are merely mediocre. The original Game Boy was not a powerful system, and obviously, that cannot be helped. Character sprites are very limited, with not much variety. Sound is pretty repetitive, and low quality as well.
Final Fantasy Legend, nevertheless, is an at-least decent RPG for today's standards. However, if you are looking for an epic storyline, or another episode of the Final Fantasy series we see today, you won't find that here. But, give it a shot. I'm sure you can find it on eBay, dirt cheap.