I have tried using 3D Touch and find it more of pain than it is worth. I don't like it on the phone, the watch, nor the trackpad. If there were relevant features that came from it, then I may try to take the time to learn the muscle memory required, but I have not really seen anything useful. I mean in Things is it really any easier to 3D Touch and press +To Do than it is to launch the app and hit the giant +? Maybe I need to take a fresh look at it, but most of the options for 3D Touch don't really make things faster or easier. The other issue is that I do not want to rely on something that is not on every platform. For example if I 3D Touch on the phone to start an email, I would want to replicate that on the iPad and cannot. Having two different ways of doing the same thing on essentially the same OS but different devices is not good design.
It was a gimmick that developers have collectively ignored. Unfortunately, that is a lot of the features Apple seems to be adding these days. TouchBar, 3D Touch, "thin", and even the ECG are just things they can market to make people think they have to have it when in reality it is a feature that few will use and will get little to no support from developers because it does not really add anything to the experience.
**Before someone goes off on the ECG being a lifesaving feature. All I am saying is that an exceedingly small number of people will actually take advantage of it, and for the vast majority it may as well not be there. I know for some it will be great, but that is a tiny minority, yet everyone is having to pay for it, and Apple are trying to scare you into thinking you need it, or more accurately, your parents need it, so they can sell the watch.