Graphics: similar with Fallout Shelter (not the online version). The character cards artwork is really nice though (and animated). Somehow they make the men beefy and the woman looks pretty. For people who played original fallout series (1, 2, 3, NV, 4) they might get surprised.
Sound: this game sound is quite similar with original Shelter as they might re used the same data. Never really bother about it.
Gameplay: this is a gacha, character collecting, micromanaging, semi autos type of game. The game itself is how you manage your Vault as an Overseer. You can expand your Vault, gather resources and recruit wastelanders to be your dweller. The game auto features is when you battle, outside of it you have to micromanage yourself. And yes, you can progress lots easier if you have SSR character. It depends on your luck or your wallet.
WARNING: If you NEVER and plan to play Fallout series, some of the character profile in this game will give you MAJOR spoilers.
Storyline: never really care about it. To put it simply you are an Overseer of the Vault. Previous Overseer handed his position to you but went missing while taking the energy core of some kind, which will doom you Vault. And now, you are tracking him down. The area setting that they use is Fallout 4 world (Boston).
Value: this is might not be everyone cup of coffee. Those who haven't play original Fallout Shelter might take time to learn on how to play. Once you get a hang of it, it is quite fun. Lots of micromanaging to do. Overall it is a solid good game for mobile.