I'm definitely in the group that reads on my Android phone, because I don't want to carry two devices. So I might look as if I'm in the "playing games" group, but I'm really reading.
I save my dedicated Sony Reader for when I know I am going to need the longer battery life (e.g. long trips) or when I know I'll be reading in the sun (i.e. the beach).
I do know that when I travel by air, I see LOTS of e-readers - probably partly due to economics (if you can afford a plane ticket, you can probably afford an e-reader - and the books for it
) and maybe partly due to the longer battery life for (presumably) longer trips.