I wish the One could pair with a Play:1 for a stereo pair. I already have a Play:1 in my living room, and was going to buy a second one for the other side of the room. Wouldn't it make sense to be able to add a One and get both the stereo pair and the voice control?
I can pair TWO Play One's, of course, but you don't need two mics in the same room. Or I could get a second Play:1 for the stereo pair and forego the voice control.
I hope people realize that in addition to getting a great sounding individual speaker, buying into the Sonos ecosystem gets you started into a very capable whole-home-audio solution. Too many reviews try to compare Sonos as if it was competing with a standalone Bluetooth speaker, and forget that Sonos is capable of much more than just a "push" audio device.
With AirPlay 2 coming, you can get whole-home audio without being locked into any one speaker manufacturer. As long as whatever speakers you buy are AP2 compatible, you're good to go and don't need to rely on one company for all of your speakers. For instance, a Sonos One would be alright for something like a bathroom speaker, but for the living room I want something far more substantial.