MG Siegler, writing on 3D Touch and the iPhone 6s:
There’s been a lot of talk in the past couple of years about the great “un-bundling” of apps. That is, big, bloated apps that spin off certain features into their own apps. For some massive services, like Facebook, this makes sense. For the vast majority of apps, this makes no sense. It’s hard enough to get people to download one app, let alone two or three. Instead, what these developers should do is utilize 3D Touch to create one-touch access to certain functionality. Brilliant OS-level move by Apple.
In the few days I've spent with the 6s so far – I'm moving to a 6s Plus this weekend – this is exactly what I've noticed, too. 3D Touch quick actions on the Home screen give developers a chance to unbundle their app features and navigation points, exposing them to users in a new, convenient way.
A good example of this is Apple's Photos app: if you 3D Touch the icon, you get a menu that, among other options, contains a 'One Year Ago' shortcut. The ability to view photos from the same day in the past has been explored as a standalone app concept in a variety of ways (see: Photo Flashback or Timehop). In Apple's Photos, this isn't even a proper screen – it's a search filter. It could be easily missed by users, but its utility is clear (especially if combined with Live Photos a year from now). 3D Touch brings fast access to that feature without needing a separate app. In this sense, 3D Touch as an interface for the deep link has potential, and I'm curious to see how developers will further explore it.