There are a few cases where it's really handy - the application I use most is the shopping list: while making stuff in the kitchen and noting I'm running low on something, I just sing out "add this to the shopping list" and it's done. Extremely convenient. I've also started using a dot as my alarm clock as it's easier to speak the time than to juggle the up/down buttons or even "alexa stop" than to groggily find the right button on the clock. I also use it where I don't have an alarm clock, e.g. reading, where I set an alarm to remind me it's time to go to bed (books are the biggest hazard to a full night's sleep!)
The voice interface is nearly trivial to use - I've written several apps, interfacing to my weather station and solar panels for example, and it's very convenient to "ask my weather station current temperature" or "how much rain we got today". That sort of thing is not going to be common though as you have to have a local server to get to the data.
The downside is things like my friends have too much fun putting weird things on my shopping list. The first thing I did was disable the ability to order things for just that sort of reason.