I came into this game without playing any of the other newer fire emblem games. The last ones i played were from the GBA era. Figured i should say that to state that i have a bias.
This game is largely a daily life simulator and a large portion of your time will be spent doing daily activities that are meant to help you bond with other characters. (Having tea, eating meals with them, choir practice, etc.) These daily life mechanics are not very well fleshed out and are more of a time waster than anything. Unfortunately, it is hard to improve your units unless you partake in these activities; as the game was designed for you to participate in them. As a person who bought this thinking it would be a tile based tactical game, i was largely disappointed that these mechanics were implemented.
Additionally, there are a large number of fetch quest in the game. There isn't much to say about this. It's the classic go here and talk to this person type of quest, so take that as you will.
The premise of the game is that you are a mercenary that was unceremoniously made a professor in the continent's most prestigious school after you saved 3 student's lives. Your students are your battle units. There is a large ammount of customizability to your battle units. It can be overwelming and hard to know how to spec your students, but overall it works well.
When the combat occurs, it is very fun. However, there are many mechanics that are complicated or not very well explained. As such, i found that when the game introduced me to new mechanics, i would have no idea how they worked.
Without spoilers, i found the story to be lackluster and didn't quite enjoy the characters.
Overall, do not buy this if you are looking for a tactical game akin to the classical fire emblem games. Instead i would look towards X Com for a challenging alien based tactical game, or Valkyria Chronicles 4 for a more militaristic tactical game.
However, if you enjoy daily life sims with intermittent fights; then this game might be up your alley.