One of the benefits of working at a retail job is being the first to see things come through when they happen. Yesterday the Nintendo rep for my area updated the Wii U display to include a playable demo for Hyrule Warriors.
The demo features 3 playable characters: Link, Zelda, and Midna. The preview takes you through an early mission of the game, giving you waves of Moblins to mow through with the various weapons the main cast uses. The frantic Dynasty Warriors-style arena combat leads up to a confrontation with King Dodongo, the second boss from Ocarina of Time.
I played through it a couple of times, and seeing it in action definitely got me excited for the finished product. Playing as characters other than Link in a Zelda game has a lot of novelty, and the robust roster is definitely a huge selling point.
Look for the demo at your local Target. The game releases in North America on September 26th.
EDIT: Some fine folks over on the Wii U reddit board pointed out that this demo is available at select Gamestops and Best Buys, as well!