Just finished File 9 in Astral Chain and holy moly, this game is epic. Unless the last three files are bad, it's worthy to stand alongside the likes of Bayonetta 1 + 2 and Vanquish as one of Platinum's best.
Also, it took me til now to realize there's sprint and slide commands haha. If the game ever told me, I forgot. XD
I thought the low point of the game is chapter 6 because it's so damn long relative to the others. Astral Chain closes out on a high note, so the final two chapters shouldn't disappoint you. Yes, only two.
File 12 is post-game where you can freely move in the office to talk to everyone again, but first and foremost it's all about accepting a huge amount of combat challenges from Olive. So there's no more balanced content anymore as the focus shifts entirely to the combat gameplay. If you've enjoyed that, there's plenty more to do in the game, but take note that the difficulty level is predetermined, so eventually it gets brutal. Should be roughly 20 challenges on medium difficulty, roughly 20 on medium-hard and then about 30 which are tough stuff.