I upgraded just one device to the new app. Most functions work for me with no issues. What I can not accomplish on the app, I do it on my Mac, which has the old app installed. My music library is functional, minus the few things that have been taken away, like the search function.

I like the new look, even though its a learning curve. 

I have connected to two other systems at a friends house and at a recreation building. One of them is WIFI only and the other has wired components with a few speakers using Sonosnet.

I used the app for hours at both places without losing connectivity with either system

No. I do not regret upgrading. I am excited to see what the app will be capable of when all functionality has been restored.

I suspect, when it’s sorted, having the search function accessible on the home screen will be useful for a lot of people that use search. Early days but I don’t think it will make any difference for me even when muscle memory kicks in. I probably won’t want to use the home screen but have the room screen up. I’m sure Sonos is pulling data on all that so I expect many will like it once they get use it particularly if you use streaming or have a very big library.

I don't have any issues with the app. It's one of those things that I use to set once and barely ever open again. However one thing I'm missing the sub EQ options for wired subs connected to Sonos amp.

Thanks.