I noticed that when trying to power off, I expected the device to react instantly while still holding the slider. Then realized, that if I pull the slider, hold it for a second, and release - it will react a few moments later after releasing. Holding it longer does not help.
In daily use I only need that button to wake up from sleep. I never power off except for reboot after installing plugin. It goes to sleep after a while by itself and since when I stop reading I won't be flipping pages it probably would not make a big difference if I manually put it to sleep before the timeout.
With the tweaks plugin I can even power off by menu, if I want to.
It seems many problems are more about what one expects the device to behave like rather than a malfunction. The most convenient use creates the least trouble without actually making a big difference in battery-usage: let it go to sleep by timer, never power off; pull power-button and release quickly to wake up from sleep - done! All settings stay put, you return to exactly the page where you left off... At least for me it works fine that way...
