Story-wise, the original Nier is an excellent game. While the gameplay suffers from the usual issues with camera angles that were endemic to most of the ps2 and ps3 era action-jrpgs, it was more than solid enough for a solo title more focused on plot than gameplay.
Despite the somewhat iffy nature of English dubs, I found Nier's cast to be superlative. The titular protagonist, Nier was a man with a very clear-cut motive and a powerful driving personality that was constantly razor-focused on his daughter's well-being and, later, that of his friends and companions.
Kaine, the game's sole heroine, is a foul-mouthed girl possessed by an insane serial-killer Shadow. Throughout much of the game, her role is to kick characters' butts when they start to brood, but, depending on the ending you get, her role changes drastically. Like many such characters with dark personalities and foul mouths in jrpgs, she has a heart of gold (though it is really, really hidden outside of specific moments).
Emil, the sole character seen in both Nier games, is a young man in the original game, suffering from blindness and from numerous other issues. He is the most innocent of the characters, with the possible exception of the oft-missing Yona, serving as a strong contrast to the somewhat antagonistic relationship between Nier, Grimoire Weiss, and Kaine.