You do realise that it matters not what refresh its running all the time, as long as it responds to user controls at a faster response than a flat 60hz, that's all that matters. If everything appears to operate smoother than a 60hz (which it most definitely does), the user will find the experience more pleasurable. The fact that it achieves this desired effect without using anymore power than a flat 60hz makes it all the better.
The problem is you need an app to tell when it's running at 120hz? I don't since I can tell by usage just flicking through the system. It's very easy to spot the difference in smoothness from 60hz to 120hz. Scrolling text on pages, videos through YouTube etc, that whole UI is enhanced by 120hz. When one gets used to it, it makes 60hz phones feel sluggish and dated.