- use any rom with the official DS emulator and enable 2x scaling, full brightness, etc with a small ini file edit.
- inject ROMs into SNES, GBA, n64, NES VC titles and fix the brightness/blurring issues (these are parameters set by nintendo purposefully and can be fixed).
- back up your digital and physical games.
- load your games from SD, including any hacks you want. There's already undub patches available for games like Xenoblade. You can play them now! All Wii U backups are uncompressed folders and files. Want to change the music on a game? They're pretty much all in brstm format! Go ahead! Play some smash bros to the music of slayer!
- Use a keyboard and mouse for FPS games.
- Use a dualshock 3, 4 and GameCube controllers as the gamepad input. You can play the entire Wii U library with a Dualshock 4 if you wanted! Or play Mario Kart or Zelda with a Wavebird!
And that's just what's available now in these early days. Just wait until iosu is fully exploited. And retroarch is an inevitability.
Not yet. For quite convoluted reasoning which could be summed up as "Smash for Wii U uses SD card for user accessible files but nothing 'regular' does it with USB drives", hypervisor breaking is required for accessing the latter. Accidentally, initially scene was sure NAS drives would be the easiest thing, then USB, then SD... but they were wrong.