This game is clearly one of the best role-playing games on the old black-and-white Gameboy.
In the graphics department, Final Fantasy Legend II is extremely advanced for a Gameboy game, let alone a Gameboy role-playing game. Whle the character spries and monster designs are somewhat lacking, it's the graphical designs of the game's environment that make it stand out above the rest. Not only do you have water that is tiding and ebbing, but also some of the dungeon walls are completely advanced. For example, in one dungeon, the walls look alot like stallagmites, giving it a authentic feel of a cave.
Regarding sounds and music, it's excellent, but could do better. The game has a nice array of sound effect. Also, the game's soundtrack is one of the best to appear on a Gameboy game. There are so many memorable tunes in the soundtrack to where you might be humming them as you go along.
As far as controls are concerned, the game is basically the same as Final Fantasy Legend I, but with a few tweaks. While you can go around town buying weapons and armor, you simply press the A button to talk to people in this game, as opposed to just running into people in the first game, which caused for some unintended and unneccessary conversations. Also, in battle, you can still attack enemies by type.
Gameplay-wise, Final Fantasy Legend II is a ton of fun. While the later battles in the game become very difficult and gaining stats take a much longer time than in the previous game, it makes up for it and then some more in the form of a more fleshed-out storyline and a much larger game world than in FFLI. An interesting addition to the game is the ability to play as a robot, to go along with the usual human, mutant and monster classes.
Overall, Final Fantasy Legend II is one of the best Gameboy RPGs you can buy. You really can't find a much better role-playing game series on the old Gameboy than the Final Fantasy Legend series.