At Nintendo World in Japan, Masahiro Sakurai hosted a demonstration of Kid Icarus: Uprising. There are a couple of videos online; one of aerial gameplay and another of ground-based gameplay. The two modes look significantly different from each other. Here's footage of a flying section:
Note how you can hear Sakurai make a direct comparison to the game Space Harrier. The ground portions, on the other hand, allow more freedom of movement:
It looks like the labyrinthine dungeons that drove people insane in the old NES game are being replaced with something more straight-forward and filled with lots and lots (and lots) of straight-up shooting.