I bought my parents, who are in their 70s, an Echo a couple of years ago. They love it, although my mum uses it the most.
They mostly use it to play music, cos I linked it to my Amazon Prime account, which I personally wasn't using for music purposes. The sound quality is surprisingly rich for such a small device (it's the full sized Echo though, not one of these mini ones). The main downside is that now when I log into my Amazon account and look at my Prime Music page, it looks like I have the worst taste in music ever.

If you have more than one you can do multi-room playback, a bit like what the Sonos systems offer (but not as good, obviously).
They also use it to set timers when cooking and to get the weather forecast.
You can do a lot with them if you have the right gear. If you have the right Logitech Harmony remote, you can use the Echo to control all of the functions that offers. If you run Plex as a media server, you can control that with your voice. You can buy Echo Buttons, which are big light up buttons, and use them to play games, like quiz games. You can use it to find your phone. There's various "skills" you can add.