Disappointing doesn't even cover it. The worst of gacha combined with the most phoned-in story Taro's put to paper, with a pace so ploddingly slow you'll fall asleep before you even unlock the main menu. Extending draken/nier's weapon stories to be a main mechanic backfires in a huge way.
Barely interactable, your avatar runs from one level gate to the next, the game begging you to put money into its loot roulette. There's no strategy, not even any real play: ultimately it's just a money vacuum.
Gacha is a poisoned well. Even the games that are entertaining (world flipper, love live, bandori) would be better without it, and Nier represents the very worst. A desolate, sinister creativity pit, it's sole purpose to empty lonely Japanese salarymen's wallets.