So the game is meh.
Gameplay wise is quite good, the problem is the lack of information, like it just throws you into the world and good luck. That may be the reason why so many people find it hard. Besides the combinations also lack explanation. When combining units it just tells what is the unit, but it does not explain much, like how the black mages stun.
Having said that the difficulty is reasonable, but you have to understand mechanics. And since the game doesn't explain it. Is trial and error. Nevertheless all the game is clearable without cheats, i did it. But it will take a few tries of combining to know which are the units and how to use them, on top of knowing the enemy and surroundings.
Finally I would have give 3 stars if all the tries were worth it. But come one there are only 6 scenes, for all the time spend. Not worth it.