The convention is that it's in the top left and that the "swipe rightward from the left edge of the screen" gesture also goes back. Most apps work like this, and it's not actually a problem in my experience. I can't actually remember seeing an app which puts the back button in the bottom right...
With apps which follow the convention, I don't miss a hardware back button (or, as is more common in Android these days, a software back button in an OS-provided bar at the bottom of the screen). Swiping from the left edge of the screen feels pretty good. But Android's approach is probably better at providing a decent UX with terrible apps.
With apps which follow the convention, I don't miss a hardware back button (or, as is more common in Android these days, a software back button in an OS-provided bar at the bottom of the screen). Swiping from the left edge of the screen feels pretty good. But Android's approach is probably better at providing a decent UX with terrible apps.