This has always been the dividing issue for most fans about this game, so simply what is it that you hate about it or what was it that you love about it? You can even list both!

Love

I love the amount of control it gives me for customizing my characters and once you factor in the equipment system, you get some rather deep customization for an NES game.

Amusingly, I don't mind beating up my characters to get stronger, simply because leveling naturally is time consuming and the game is still actually hard, so the amusing oversight allows me to actually set the difficulty of the game for myself.

The balancing factor of the game is ingenious. It's amusing that what you equip your character with can really easily change their role in the game for you and easily knock you into one of the job roles from FFI.

Weapon proficiency, I don't know what it is but I love games that give me bonuses for sticking to a weapon or equipment set-up.

Hate

Leveling magic is a total pain, and while you don't need the levels to be very high to beat the game. Later remakes give you some initiative to try to maximize the spells cause they actually change the spell animations greatly every few levels to create a sense of a Tier system like later FF games.

The game is easy to break, the ability to beat your own party up or select/cancel spells can easily not only drive the player mad with tedious fatigue but make the game a joke in terms of difficulty. Don't even get me started on the Blood Swords...

Spears are kind of useless. An interesting weapon to add, but in my experience out of all the weapons, the spear offers no advantage over other weapons.