I've also been very happy with the Alexa & Sonos integration & Indigo Sonos plugin. All three work very well together under my testing for some time.
The new Alexa / Sonos integration is,
by no means, a replacement for many of the home automation integrations of Nick's excellent
Sonos Indigo Plugin. While I now use Alexa to start a lot of the music listening in the house, Sonos plugin allows for amps and subwoofers to power up / power down based upon player status, play an important role in scenes, actions, and other triggers.
Alexa's strength is playing Pandora, radio stations, and other sources from a voice command. "Alexa, play {radio paradise} in the kitchen" works very well. There's a "feature" that some may find annoying, however, speaking to Alexa will temporarily drop the volume in all of your Sonos zones. So, when kids say "Alexa, play KidzBop in the Family Room," or "Alexa, next" or "Alexa, Volume 4 in the FR" ... Sonos will drop the volume (completely or nearly completely) of whatever I'm playing in any and all other zones for a couple seconds for each and every command or inquiry she receives.
Still, as a Sonos fan since 2007, this is a great upgrade to a great whole house music system.