I've been playing this game for a while and it's pretty fun. They give you a lot of resources so actually you barely need to pay any money in to get good stuff, plus it's almost entirely PvE so really your loadout and optimization doesn't matter much.
But I would emphasize that it is absolutely a gacha game. If you have problems with gambling or those sorts of addictions you absolutely should not play it. Like I said you can play without spending money but the option to spend money is definitely there and it is real expensive for a lot of the options. It's not worth the risk if you do have these problems, after all they are just animated pictures. There's plenty of that for free on the internet.
But just for some added content I would say Lan Fei is another character who is on the upper end of the busty scale.