What you will like:
Community - Very supportive and arguably one of the most helpful communities I've joined this year. Ask and you shall receive. Also, try sniffing channel 8 for mindless fun.
Simplicity - The game solved one of gacha's biggest problems: Multiple clickables in a page. The interface is very minimal and the gamer's focus is geared towards Esper building.
FTP Friendly - The game, as of this review, does not swamp you to buy. You can be strong just by grinding daily. Arena and Point War matching is surprisingly fair. It does not discourage you by matching with somebody stronger like most gachas. You have to move up the ranks if you want to fight stronger opponents in Point Rank matches.