Amazon's use for it is to tie you into their ecosystem and sell you stuff. Just like all their other electronic devices. But if you have interconnected systems you can do things like turn your lights on and off, set the heating temperature, set reminders, play music, play stuff on your telly, ask questions.
Edit: I've got the Google Home coming for Christmas for myself. But I've already got Nest thermostat, Phillips Hue lights, Logitech remotes as well as Chromecast set up in the house. Probably about a grand all in for my set up.