Gets better with each new release!
With Dwarf Fortress there's so many different things you can do, and sometimes even the smallest action can lead to vastly different, just like real life. And the opportunities presented by the game are amazing! It only takes a quick search for community plays of this game, such as Boatmurdered or Nist Akath, to understand the story-telling potential of Dwarf Fortress.
With each new release, the Adams brothers implement new ideas that further the creativeness with which people can play the game. And that's what makes it so worthwhile.
The behaviours of the dwarves and other creatures generally seem more random than not. However, I won't point out any specific issue with AI, because that part of the game is constantly tweaked, and a problem in one release might be fixed (or turn to be beneficial) later on.
The Bottom Line
This game is a work in progress, and a moving target, but that's because creating stories through game play can never be finished. Despite its basic graphics, in this game lies something so profound that is hard to find in most professional games. Play this game.