The game tells the story before Final Fantasy 7 and gives more context and explanation for Final Fantasy 7: Remake. The main character Zack is fun, despite or because of his cockiness. The other new characters are fine and tragic, but their characterisation is rather superficial.
Final Fantasy 7: Crisis Core and Remake use the same graphics assets, but the levels and environments in Crisis Core are less detailed and very limited in scope.
Gameplay-wise, both games use a similar action-oriented combat system. Crisis Core adds a combat wheel (slot machine) that allows the player to randomly activate powerful abilities. It also allows the player to level up randomly, which is a rather controversial mechanic because of its randomness.
Moreover, the player can fuse materia to upgrade or create new materia for new abilities, which is maybe the best game mechanic in this game.
In addition to the overall good main story, the player can complete side missions, most of which have no story at all. These missions are more about leveling up your character and collecting more powerful items. This is fun for a while, as these missions are usually very short, but as there is no story and there are hundreds of missions, they become repetitive and less interesting over time. Another problem with the side missions is that the difficulty varies between missions of the same difficulty rating. If you do (grind) a lot of these missions, Zack becomes over-powered, which makes the main quests too easy and the combat too repetitive, as you only have to use two abilities over and over again to insta-win most encounters.
Overall, this is a good game story-wise, but with rather repetitive gameplay elements. I recommend playing it before playing Final Fantasy 7: Remake.

i love zack fair.

10/10, would cry again.