So the X is my first experience with 3D Touch and after a month I am mixed on the feature.
The main thing is that it's completely inconsistent from app to app so it's impossible to rely on it the way you think you might.
Something like Camera, an app divided with several distinct features, it's really useful, can take you straight into the Video camera, for example. Nice time saver. But something like Clock, similarly divided with several distinct features, it takes you to "Create Alarm" instead of just the list of "Alarms" which is far more useful if you are someone who wakes up at the same time each day, rarely sets a new alarm, and just wants to quickly tap the slider.
Worse, use 3D Touch on Phone and you get a shortcut to "Search For Contact", pretty awesome. But 3D Touch on Contacts and you don't get "Search For Contact" at all. Why would you want to search for a contact on the Phone but not in Contacts?
The inconsistencies make 3D Touch unreliable, untrustworthy, might as well just tap on the icon the old school way and get there through the app.