Play it if: you're in the mood for a short, high-concept piece of sci-fi.
Don't play it if: you're in the mood for puzzles or much in the way of interactivity.
World Builder seems to draw strong influence from the Isaac Asimov short story "The Last Question". I could be wrong about that, but given the common themes of man, machine, and cosmic godhood, I think I could be forgiven for drawing the comparison.
Perhaps appropriately, World Builder as a narrative shares most of The Last Question's strengths and weaknesses. It succeeds in moments where it evokes grand imagery and higher powers: this is a universe inhabited by machine intelligences, planetary designs and would-be gods. The prose is acceptable, perhaps under-implemented in places but functional in conveying the settings and possessed of occasional moments of striking imagery. The scope of the story requires that the characters speak with Tolkienic grandiosity, which while appropriate does serve to distance the player from any deep emotional connection with the characters, especially given the short length of the game; beside their immediate goals, the characters are generally ciphers. This is not entirely a flaw in a short game emphasizing high-concept imagery: "The Last Question" also had fairly flat and static characters, and it's (by most standards) a gem of sci-fi short stories (Asimov's personal favorite, incidentally, and my favorite short story of his ouevre).
As a game, there's not much to speak of. There are no real puzzles and no real gameplay stakes - as far as I can tell, there's no way to lose, though perhaps the game was just very forgiving. This is understandable when dealing with a PC who is close to apotheosis, but it does make me wonder if the story of "World Builder" wouldn't have been better served as straightforward fiction than as IF.
Still, a diverting five minutes of your time.