Development

• Star Fox U is being developed by Miyamoto alongside Project Giant Robot and Project Guard at EAD Group No. 5.
• All three have been prototyped entirely at Nintendo.
• An external developer will help complete Star Fox.
• A small team experimented on Star Fox, unsuccessfully, for six years on Wii. About 6-10 months ago, the project and all assets moved to Wii U.
• Select members of the press got to play the title at E3.
• Miyamoto wants "to bring this to the market very soon" and is aiming to release the game "within a year."

Gameplay

• Miyamoto referenced the TV show Thunderbirds as an inspiration, saying this Star Fox will be less like a movie and more like a TV show.
• The game will be structured episodically (but not necessarily released episodically).
• Miyamoto said you can think of it as "primetime programming" (the tried-and-true Star Fox gameplay) supplemented by "late-night programming" (quirkier, more experimental fare).
• The tower defense prototype Project Guard features Star Fox insignia, and Miyamoto hinted this may end up in Star Fox as an example of the "late-night programming."
• This Star Fox is also like Thunderbirds in that the player will use a variety of vehicles and mechs.
• Your Arwing can touch down on the ground and transform into the Landmaster.
• Players can also control a slow-moving helicopter and simultaneously collect various items on platforms using a robot on a tether. The robot can also fire at enemies to defend itself.
• You will have all-range mode in the Arwing, which select members of the press got to try in a dogfight against Star Wolf.
• You will also have what Miyamoto calls "valley mode," where you're on-rails. This time, however, the GamePad's gyro allows you to aim in one direction while flying in another, rather than your aim always being locked to your path of flight.
• The GamePad's screen also provides an alternate point of view from the ship's cockpit, which will allow you to see details in the environment that you won't see on the TV, and vice-versa, so you'll have to look at both screens in order to succeed.
• The game will also feature cutscenes that play out across both screens (TV and GamePad), giving you multiple perspectives on the situation.
• Slippy, Peppy and Falco also communicate to you through the speakers on the GamePad.
• There will also be a co-op mode where one player can control the vehicle on the TV using the Pro Controller, and the other player can be the gunner using the GamePad. The tethered robot is one example of this mode.

Source: http://www.gamnesia.com/news/everything-we-know-about-star-fox-u#.U7GtAyhBls1

The game so far sounds interesting. Hopefully we get to see the game soon.

Nothing has been confirmed as far as story goes, but from what the people who've played the demo said, there were only SF/SF64 characters showing up. Since this is Miyamoto doing the game and him not being involved in any of the other 3 in the series, I believe this will be the case.

And I'd be relieved as well.

I'm very skeptical for the game though, but I believe Miyamoto won't ruin this franchise twice.