I use the Siri ChatGPT integration pretty consistently on my Mac. I like the keybinds for it, and I also like that if Siri has the answer for my question it's usually instant; when it doesn't, it sends it off to ChatGPT for me.

As for their other stuff, I use Apple's email inbox summary feature constantly, and I occasionally use the writing tools AI stuff just to proofread long text I've written to make sure there aren't any glaring mistakes I'm missing.