A full description of all the updates can found on the game page.  Suffice it to say, the demo has gone through quite the overhaul, including:

• New OST which updates and replaces several of the regular tracks with new ones
• New dungeon.
• Tweaks and minor updates to the various tile sheets.
• Upgrades to the menu system, including the ability to see what items can do and what status ailments the player can resist.
• A couple removed weapons for the demo have been restored. A couple new equipment pieces now appear in the final area of the game.
• The music looping glitch has been identified and fixed. This is the first project to receive the fix.