My experience with both devices is that there's no one Big Thing, except maybe music. There's a lot of stuff that just works surprisingly well by voice. Quoting my daughter: "Hey, Google, play Puff the Magic Dragon" - "What's the weather today?" - "Turn on/off the lights" - "Set a timer for 5 minutes" - "What's 17 tablespoons in cups?" - "How long does it take light to get to Mars?"
It's probably not smartphone big. But I think that in the long term, we're going to find that some kind of voice-based interactive device like this will become very common.
I cook a lot, timing is important.
I have fun playing games with my kids teaching them trivia, Google Home does that while we are free to do other things.
We listen to a lot of different music. Google at home allow me to stream from Spotify simply by saying the type i want.
My wife likes to listen to radio, she just tell Google at home to start a radio station.
Listening to the news, google does a pretty good job assembling what is most important during the day.
You can ask it to play the latest "Startups for the rest of us" podcast simply by asking it to play that.
You can ask it when you next flight is.
How long it's going to take to get to somewhere.
You can add things to a shopping list which is important when you are family.
And these are just things that it does out of the box. I don't care about switching on lights which it also can do and turn the heat up or down.
What I think most of you realize is that just like the touchscreen removed a layer of abstraction to access technology because it allow for things humans do naturally. So does the voice. It's extremely intuitive as there is nothing to learn. As voice gets better and better it's going to change a lot of things.
The sales numbers of Alexa is pretty telling too and this is from all sorts of people like my parents in law who now have one they use and understand.
I don't care whether it's going to be the next big thing, but to claim as the parent did that voice is a bad interface is simply as wrong as it can be and to claim there is no value in what it can besides a few things, well it turns out at least for my family those few things are pretty useful.
Telling Alexa "send me some paper towels" only works if you have established a protocol in writing with Amazon (i.e. I want a 8 pack of jumbo bounty).
Your use case "how is the weather" is useful, but is it useful enough to be "the next big thing"? It may be big, but not smartphone big.