It inspired a whole genre (I know Demon's Souls came first, but Dark Souls is really what sent the genre to the mainstream). Even among the now hundreds of "souls-like" games there are today, Dark Souls stands among them as game that feels incredibly unique. The biggest criticism I could give Dark Souls is that it can sometimes feel a bit too cryptic and leave the player with no idea what they're supposed to be doing, especially if it's their first Souls game. But the story, world, characters, enemy designs, combat, and especially the level design is all masterfully done.