Everyone's talking about 3D touch, but the feature that has me really excited is the one that makes it possible—the taptic engine. Bret Victor has a fantastic essay on how the tactile capabilities of our hands are woefully unused in current interaction design, and I think this is the first big step to take advantage of them. Simple things like small bumps as you reorder list items go a loooooong way toward making software feel more real. Can't wait until Apple opens up this API.
Yep, I agree. That's why what excites me most about 3D Touch isn't the binary state that's used as a right click, but the dynamic actions you can perform by measuring the amount of force applied. That opens some great possibilities.