You can finish this game in about 15-20 minutes ... but almost certainly you'll want to replay it at least once. Can't really say much about the story without spoiling it, except that I recommend it. Well written, simple and fast paced, but there are some twists to the plot that might not be obvious until replay.
After ending the game for the first time you'll realize how clever the author has been on delivering that sense of urgency that will trick you into overlooking those details which are important to grasp what's going on — but being tricked in this game is part of the fun of playing it.
Nice.