One interesting thing he brought up is that as a developer, you can't develop as if everyone is using a 3D Touch device, because they aren't so you just add some enhancements to your product for the 6S(+) users.<p>This means among other things, it will be easier for Apple to abandon the idea if it ends up not being worth it, since it is such a small part of the UX of the devices, or even replace it with some other mode of interaction.
The first video really impressed me. It genuinely looks like he is depressing a 3D button into the screen. I was pretty skeptical of the name "3D Touch" at first, but that video sells the idea better than Apple did.