Is the 970 with 6.18 stable enough to purchase?

It is not. I also don’t use custom watch faces and apps and didn’t have any issues for the past month. I thought I was lucky, but started seeing battery issues a few days ago and the watch finally crashed during an activity today (luckily nothing important). I don’t trust it anymore and I am switching away. If you want a rock solid watch, go for 965 or another brand.

I am 100% satisfied. Stock watch face, touch disabled (I am kind of old fashioned), pulse and sleep tracking enabled. 3 gps enabled exercises per week with HRM pro paired. Works like a charm. Nothing to complain. I have always on display switched off and I get roughly 2 weeks of battery life out of one charge.

No problems with mine, custom watch face

Except for reboots when trying to use phone assistant (but this is not the most important feature of the watch at all) my watch works like a charm. I'm using stock watch face and the only installed app is the brand new Google Maps and Spotify.

Is it stable and does it fully work. Two very different questions. 

Yep which is why it went back for me. I'm glad it did as well as I can't believe only one hot fix has been released in 6 weeks! 

Since the update mine has been fine. No more ghost touches. Only thing mine still does is about 25% of the time it reboots when using virtual assistant. Garmin hasn't released a fix for that yet. I don't have any custom apps or watch faces and only use it for running. 

Does your voice assistant work reliably?

does yours make an occasional popping noise?

What about changing volume levels permanently?