I've played this for 3 years, and will likely continue playing for another 5. As a game, it's fairly great all things considered, at least if you want an open world action game with a lot of variety in team composition. New content is shot out at a rate I can't even really fathom. The game earns billions of dollars a year, but at least it looks and feels like it.
The problem comes with the gacha / live service aspects. The gacha asks you either spend $400 to guarantee ONE 5-star character, or grind for 8 months and save enough to even get a chance when their gacha banner comes around, if at all. Don't even get me started on the weapon banner.
The live service end game on the other hand, kind of just boils down to farming the same challenge for 2 years at a chance to get minute stat boosts on your character. The Artifact system is perhaps the worst set of RNG statistic setups I've ever seen in any game.
I could go on for an hour about both the good and bad, but I'd rather just keep this review at that. I would never recommend this game due to the problems that arise with what the game asks of you.