Don't get me wrong. This is a very fine sounding speaker and easy to set up. That's why it gets four and not three. It gets a four, but not five, because I'd bought this primarily as a voice-controllable bedroom speaker. The Sonos alarm is fine but it's not voice controllable. I specifically didn't want to have to use my phone to manipulate alarms, in an attempt to banish it from the bedroom. Google assistant alarms aren't available either though. What's particularly egregious about this is that you can set a GA alarm with your voice and the speaker blithely reports that the alarm has been set, repeating the time and everything. Only it hasn't set anything. GA timers work as expected (go figure.) It's clearly a bug but Sonos support declined, implacably, to report it as such, preferring to call it a "feature request".
Not enough of a deal breaker to warrant sending it back (it does sound lovely). Still, arbitrarily incomplete voice control meant I couldn't use it for the purpose I bought it for. I hope to give this a five rating when the bug is fixed.
This was easy to set up and works with both Alexa and Google Assistant. You can only have one set up to respond to requests, but I have been able to set it up with Google Assistant on the Sonos and also play things on it from my Echo. The sound is pretty good but it doesn't really fill the room on its own.
Using the Sonos speaker requires configuring the Sonos app with your music accounts, regardless of whether your Google or Amazon accounts already know about them. Since setting it up, I haven't used the app, so I can't comment on that.
Only 4 stars as the microphone is much less sensitive than the other models I have (3 Sonos One version 1). You have to be within a couple of metres from this Sonos One for Alexa to work well. I don't know if it's this particular unit or version 2 in general.
The Sonos One is a great speaker, both for the usual playing of music, but also as a smart speaker to control the selection of music, or asking questions or setting timers, etc. Sound quality is good as you would expect from Sonos.
I own both the Gen 1 and Gen 2 and as it stands now, I can't tell them apart. Sonos says that the Gen 2 has a newer processor and more memory that may enable new functions in the future, so I'd buy a Gen 2 over a Gen 1 (they are still for sale in some places). I don't notice any difference in the sound or microphone performance between the two generations.
The voice control is great. I've mounted one of mine in our bathroom so being able to ask "What's in the news" and have the morning news play while taking the morning shower is handy - or music if you like. It was also nice to see that, after mounting the Sonos One upside down in the bathroom, the Sonos logo still looks the same, since Sonos is a palindrome!