Huawei's Mate S was our favorite phone of IFA for doing a lot of smart things right: improving fingerprint recognition, maximizing RF signal, and offering good low-light photo performance.

But the phone also has Force Touch, which is already on the new MacBook and Apple Watch, and may be one of the iPhone 6s's flagship features. The Mate S's implementation shows how Force Touch has a lot of potential beyond simply clicking on things, but it still needs some work.

First of all, Force Touch is only available on the highest-end, 128GB model of the Mate S. That's going to prevent developers from writing apps that take advantage of the new feature, as most buyers won't be picking up the highest-capacity version.

The most exciting Force Touch feature is Fun Scale, the app that is supposed to turn the phone into a small kitchen scale. Cool, right? It would be, but it's too restrictive. First, it says it only measures items between 3.5 and 14 ounces. The item also has to be electrically conductive, so when I put a pill bottle, a camera, or a coffee mug on it, it didn't work. Small objects were too light, and objects in plastic measuring cups were not conductive enough. It measured a metal cup, a banana, and a metal can of chili. This is a great idea, especially considering that the Mate S is water resistant, but it needs to be more flexible.

Otherwise, the phone's big use of Force Touch is in magnifying images in the Gallery, which works fine, but it's entirely unnecessary.

I have general problems with Force Touch user interfaces, in part because I remember the disastrous BlackBerry Storm series of phones (they had Force Touch; it was incomprehensible) and in part because I'm frustrated with how Apple handles Force Touch on new MacBook trackpads. Sometimes you try to tap on things, it Force Touches, and you can't figure out how to tap on things normally. I'm also completely unclear why Force Touch is superior to pinch gestures or to long press, where something new happens if you hold down your finger on something. It's an additional, unnecessary, confusing layer of interface.

Fun Scale shows a different approach to Force Touch, one that enables truly new applications. But as I said before, it has to work. Hopefully Huawei's development teams—or Apple's, for that matter—are hard at work figuring out how.