Sound: Japanese VAs are mostly famous (dunno with korean, etc). Music is good, with many action themes.
Gameplay: Immobile TPS type. With potrait orientation in smartphone, the sight is so limited, and the control which player must swipe first to initiate attack is kinda difficult.
(Wonder why it's not using gyrocontrol or direct tap).
Storyline: First thing that comes to my mind is Eighty Six anime, but android sexy girls vs rapture (legion).
Do you know, their anorganic body is more resilient than the organic one, so it's better for brutal....
And remember when commander says that rapi's head is heavy, it means that overall nikke is heavier than human, omg death by snusnu.
Value: The gacha has (unreliable) wishlist feature and no pity. Always check for daily shop. Without enough dupes, your team level will be stuck.
It's enjoyable despite all of the bugs & other problems.