Night Shift is totally stuffed. It doesn't eliminate enough blue light, which is the whole point, it interferes with my custom display calibrations, and meanwhile Apple has blocked Flux on iOS. For Mac, there's no big issue. I just will ignore Night Shift and go on using Flux.
The iPhone is a different story. I'm on jail broken 9.0.2 and missed the signing window for 10.1/10.2, so I won't be updating until Apple makes sure Night Shift fully adopts Flux features or allows Flux to return to the Sandbox. It's literally that important of a feature to me that I'll not get another iPhone without it. There are few must have apps/features I can only get outside of the Apple sandbox that are deal breakers for me if I can't have them. Flux is one of them. I'll seriously consider an Android device like a Galaxy S8 or something else based on Flux.
Night Shift sucking is kind of a big deal. It was released before ready without consulting or buying the "experts." Very un-Jobsian. Fix your crap, Tim!