I'm wondering if you somehow pinned your org to an old version. I'm, as a googler, on pre-release and Chat is obviously changing a lot. I doubt I will ever like it, but "nothing has changed" is the polar opposite of what I'm seeing.
However, I've just tried again to be sure and I'm still unable to create a group chat with someone outside my org (that I've added to a channel), unable to reply to a specific message in a conversation, unable to edit some messages. As an admin I am also unable to perform any kind of moderation in a channel (arguably, that's not a showstopper, but it is weird not to have admin rights over my organization chat). Also, switching back and forth between two conversations still shows a very noticeable delay with a spinner which really hampers the experience.
Hopefully the changes you see in the pre-release will be deployed soon and fix some of those issues.