What does it improve, in practice? For myself, I need my phone to make phone calls, take photos/videos, occasionally run apps, and to be a wifi hotspot. My iPhone 6S did all of these well enough that I only upgraded it recently because I dropped it and bent the power button. My new phone has a slightly nicer camera and better battery life, that’s about it.
I actually also do not find new phones that much of an improvement, but just to be a devil' advocate:
1. High-resolution screen, finally approaching paper (600dpi) 2. High-refresh rate screen, up to 240 fps. Once you see 60 fps, you are already hooked, and 240 is just mind-blowing. 3. High-resolution camera, 50 Mpx means that the camera actually starts to match paper (600dpi) 4. Slo-mo camera (240 fps) to match the screen. 5. Decent memory sizes. On my recent 24 Gb size memory I can actually run multiple apps in parallel, and they are not getting killed. You see, using all available memory is a competitive strategy for app developers -- when they use all the memory, their competitors are evicted from RAM and the user is less likely to receive notifications. 6. Decent sdcard size (1Tb). Same reason for the storage. App manufacturers are trying to use all available space, so that you would delete the competitor's apps in order to keep using theirs. 7. HDMI over USB -- finally you can connect a keyboard and a monitor, and get rid of your laptop, just use one device for everything.
> Once you see 60 fps, you are already hooked, and 240 is just mind-blowing.
I'm a sample size of one, but I'd rather have 20% better battery life (this would extend the life of a three year battery to roughly four years) than eye candy. Extremely aggressively glued-in batteries turning into hazardous gas packages are the only reason I replace portable computers these days.
And -given the history of such things- lack of care in system design means at year two or three, you'd find that your phone very, very inconsistently delivers 240fps. I think it's pretty widely known that once you get to somewhere around 15 or 30 FPS sudden variation in frame rate is far, far more noticeable and unpleasant than rock-solid "low" frame rate. [0]
[0] That is, a 240 FPS system that janks down to 30 FPS every few seconds is gonna be considered much less pleasant to use than one that always runs at 30 FPS.