I put it side by side with an echo dot I have. I played the same song from Spotify first, the sound was really not that good compared to the echo, it was a little tinny, hardly any bass and all round just not as good for music, which is what we usually use them for. Then I asked a few basic questions that I would usually ask Alexa on a daily basis (weather, etc) and the thinking time of the Nest was 1-2 seconds more than the Echo, not a massive problem but something I noticed which would annoy me if I'd have made the change.
I'm sure I would have liked the Nest if I hadn't already had an Echo, but it's a step back really so I'm not interested in keeping it.