I cannot understand why or how, people nag for variety or rather, lack of it thereof. They seem to conveniently forget that other than enemy types, there are the weapons each one of them wields. Same type of enemy can be an "archer" for instance, they change weapons and try to melee if you get close and stuff like that.
The imbalance is also a lie. Barbarian, especially after getting the one and only armor for him, has always quite high defense. Right timing and you can block incoming hits with weapon occasionally, too. Amazon is fast and agile, can reach enemies from longer distance. Barbarian swings more slowly than others and can be easily interrupted, unless you learn just when to start performing your combo with what weapon. The knight isn't OP, his weapons are, because they have fast hits and quick combos; besides, certain enemies especially early can easily off him (burly orcs mostly), against which Barbarian has a laugh and Amazon doesn't even let them approach. Dwarf has to "reach" the enemy and start hitting at point blank range, which is tricky, but particularly lethal and utilizes queen sword exceptionally, since the first hit usually lands (knight almost never connects the very first of the two hits the special move unleashes).
It all comes down to timing, precision and skill. Every class can be OP, if you know how to use it well. I always "awesome" through the game, unless with Dwarf, but that is because i need to save before most jumps (he is the worst jumper).
The only real flaw of this game, is badly placed special items. Ghost Medallion in Ephyra is useless for instance and in Dal Gurak's, you find it only after having killed all poison using enemies. Or crown there, for that matter.
Last but not least, people who didn't like the story, probably skipped adventuring, reading murals, discovering the runes and watching cutscenes. Breaking into a secret room and reading a carved stone in like say, Shalatuwar, makes you trully reconsider. Or seeing all starting areas and manually connect the lore fragments. Adventuring exploration and paying heed to details, like discovering the rune underground hall in island fortress, is something you do manually anyway, so it can be obviously missed. Nice insight is also provided at world map and at a new stage's beginning. This game doesn't hold your hand, it never spoon-feeds you, you have to do everything yourself, probably that is why people tend to miss many things.