The big feature in 0.13 is the addition of three new levels towards the start of the game. Look for "Tunnel Vision", "Run the Gauntlet", and "Virtual Velocity" in the level selection list, near the top.
These new levels extend the initial "Orientation Course" portion of the game, and are now included in the Demo. The Demo used to be a single level, taking maybe 5-10 minutes on average. The Demo now contains 4 levels, and is probably more like a 20-30 minute experience.