Sound: I hardly hear anything, but at least it has sound & attacking voice
Gameplay: It has AP consumption, so at least you must slighty think about party composition (every unit has different AP consumption). HP stat from every party unit is basically summed as 'one' party HP so it's no matter whomever unit get attacked (meanwhile, attack stat works per unit). It has an auto-battle system anyway. You also can enhance overall party stat with equipment & potential stone.
Storyline: Dunno, everyone is a pilot. Sky adventurers likely.
Value: There are many newbie gift. No reroll. Unit rarity isn't that significant, because stat of low rarity unit with high bond level can even outclass ssr unit with low bond level (you can increase bond level by using exact unit dupes).
Man, unit slots always full with exp fodders.