After seeing the last episode I can say that this series was a very big surprise for me.
I have been playing the game for years and read the story every time. The game has a rather good but mostly very dark story that I thought would not be too appealing for screen adaptation. On top of this the story of the first chapter (that they adapted here) is by far the veakest story out of the whole.
Despite all this this series came out above decent and is full with emotion and does justice to the characters involved.
I sat down without any expectations as I have seen the quality of several video game story adaptations before and I have to say I was surprised positively.
I even think that someone who doen't know anything about the game or players that do not read the story can have a very pleasant time as well. Of course the ones who know the characters from the game will have a much better time.
Needless to say that you should not expect Arcane levels of quality of writing or acting here but it is a decent and fun addition to the Arknights world and I strongly recommend checking it out.