The only that truly annoyed me was that CMD+click doesn't work immediately anymore but conjures some kind of intermediary menu. Haven't figured out if there's a new keystroke for it, but I'm still doing too much work in Xcode 8.

To me it was nothing but progress compared to 8 apart from that. Everything faster and better.

There is a checkbox in Xcode preferences to change it back. Not sure where as I’m on mobile, but that annoyed me to no end till I found the option.

I agree on faster and better, but still buggy. Autocomplete still regularly dies for me and requires a restart (of Xcode.)

Preferences > Navigation > "Command Click on Code"

The new key command for it is right there in the menu when it pops up. If you select the first item to do what the old command did, it's literally just to the right of the command!

Yeah....but muscle memory....

It's CMD+Control

I haven't used it much yet myself, but I did notice that one annoyance I had was fixed, regarding zooming the font onscreen.

I've used it for a couple of days now. I've seen some issues with the Simulator but I think that's not strictly related to the IDE. As far as Xcode and the editor is concerned - it's extremely quick now. Functionally also better in terms of the code editor.