SOUND- Japanese VA is fit for the role of every characters, i'm not sure in CN of it's dub VA tho, BGM sounds is quite nice i have no complain either.
GAMEPLAY- it is turn base battle, but the fun part is you can attack one or more target while the one is still executing his/her attacks. (if you play Valkyrie Profile it's something like that). yet i can't read the attack/skills description maybe there is a combo attack/effect as well.
also some characters are not build for fighting, ex. subaru will be support character only that boost stats of main character you use, you level up your main char and support char to strengthen them, daily dungeon for upgrading materials and such. (i think you know how this works). duplicate cards can breakthrough cards and increase the stats/effects of it, promote to increase the level cap by 10. (for starter you can level up them to 10 and need to promote to increase to lvl20 so on).
to unlock other dungeons for materials you need to level your account and complete some quest/mission if available.
STORYLINE- Same with the Anime or manga, it been to long since i watch s1 soo i barely remember but if you are familliar with the story you can just "skip" them, since it's japanese also, i bet few can read the story anyway.
VALUE- with lots of freebies and rewards, you can roll like x5 10 rolls early in the game to get you desire characters, if not there is a reset account something. (not sure how other manage that) therefore this game is also grindy esp. required materials to upgrade and promote. repeative battle makes you bored also. but that's what you expect for every RPG games today.
there are some in-game transaction as well like battle pass thing, there is no VIP shit so don't worry (i feel bitter about VIP) haha.
(QUESTION AND ANSWERS:)
Q. How big is the game?
A. To be exact it's 2.19gb for now expect it expand every updates.
Q. What device can run the game smooth or high setting?
A. Mid gaming phone can handle fps 60 (max) but it default to 30. switching to 60 drain battery fast, i lil heating too but the game smooth, no lag at all. and support 720p i'm not sure what's that maybe graphics or video.
i am using POCO X3 NFT no problem running the game. similar specs like snapdrag 732 /6-8gb ram or higher.
or lower end device i am not sure but maybe can play withl lowest setting and expect overheating, don't play if the game too lag or phone heating fast, it will fry the motherboard and poof bye bye phone.
(Genshin impact kill my previous phone)
Q. is there a English support language in the setting you can change?
A. No, only japanese. (English maybe soon if they want to market globally)
Q. i'm stuck at lvl10 i can't upgrade my characters, where can i find the missing materials and how to unlock them?
A. just progress in the game, you need to unlock the manor and complete some quest that npc require you to do it. the dungeon in the manor has those materials you seek. to be precise unlock stage 1-6 so on to get those materials to promote to lvl20 so on. you can repeat the stages there to farm materials. it's different from the daily dungeon section.
feel free to correct if i mistaken some info, or share some info in the comment section. thank you!