My migration from Apple Watch Series 3 to Series 9 was very smooth. My spouse did a similar migration a couple months ago to the current Watch SE, and we’re both happy to have the upgrades.
The “Walkie Talkie” feature pushed itself back into prominence on my new Watch. I recall trying it with little success 5 years ago, and then seeing that Apple had disabled it for a time:
So, with two current model Watches, a strong mesh WiFi network and a decent cellular signal, and separated by just a couple of walls, we thought we’d try it again. It worked, once. Then it refused to connect when my spouse tried to talk back to me. She’s the kind of user who will jettison anything that isn’t working because of it being a waste of time for her, so that experiment was over.
I’m wondering (and @ace this is a question that might be a good “who uses it?” poll) if this is a feature that Apple introduced as a whizzy thing years ago, and hasn’t bothered to develop other than patching a security hole.
I personally find it annoying that it was sitting there flashing an “active” icon at the top of my Watch face, but didn’t work well when I wanted to try it out.