We recently acquired new information stating that Ganon is not the antagonist this time around, since the Triforce isn’t a direct concern. Lord Ghirahim is now the main enemy who was created in a similar contrast to Ganon. A harp is now the musical instrument used by Link and with the Wii motion plus, you will use it to strum in rhythm to play it. Also, Zelda is not a princess in Skyward Sword, but a childhood friend of Link, and the story is actually placed before Ocarina of Time, focusing on the creation of the Master Sword.
During Comic-con Bill Trinen from Nintendo of America was interviewed by Gamespot explaining a system for upgrading items in Zelda: Skyward Sword. Bill explains that you will use rupees and artifacts from defeated enemies to upgrade the shield, beetle and other items. He mentions the art style of the game and motion controls first and then reveals the upgrade system details.