Device screens seem to just get bigger and bigger. In my mind the 5.5" screen like what is found on the Galaxy S6 is really the sweet spot. Of course I said this about 5" screens a few years back. Devices like the Nexus 6 can be a bit unwieldy. Large screens can be great for media consumption, but tend to cause finger and hand cramps when using on a daily basis at least that has been my experience. Tasks like reaching for a power button can also be a chore. Some manufacturers have done a good job at making the power button ergonomic, but even then having to make the extra reach can be a little annoying.
Android M has a tap to wake feature built in. The Nexus 9 comes with this feature natively, but with Android M you can chose to enable or disable it. There is even a toggle for tap to wake to easily turn the feature on and off hidden in the Nexus 5 build. It is apparently unusable on the Nexus 5 as such a feature would be a battery hog on that particular device. It will be nice to see what comes of this feature in the official release.
via Reddit