Haven't used them myself. Have colleagues with iPhones who use and like the Apple variant. But I still consider this "nerd-zone": Only for the tech-interested and the gadget-addicts.
My problem is two-fold: Yes to an assistent (and I can't afford the human kind). But No to the investment of time and mental energy into adapting a new way of working and living.
Because like Tom Gillies write: An assistant is a crutch. It makes you dependent, whether it is human or virtual. Which begs the question: Do you dare to risk making yourself dependent of one? Are you rich enough (in terms of workability) to allow yourself an increase in production at the cost of a lower marked value (because there is actually less things you can perform in the workplace and in life, if your assistent suddenly "quit" - or becomes too expensive)?
I don't like being dependent on things outside of my control. Yes, I have to live with it - but I still am not comfortable with this dependency creeping in on me.
Another way of seeing an assistant is: Leverage!
You can manage more, better, safer, and more consistent. Which has to be a good thing.
And you can even leave out the dull work tasks, maybe. But you still have to know what they are and how to do them. And my experience is that after 4-6 months of not doing some mundane task, I tend to forget I ever did it...
But what would I be interested in? Help to remember what I forgot!
I don't need a process flow optimization algorithm to turn me into a human robot, just following orders from a machine all workday long. But it would be helpful to have a daily digest of questions I asked but never got a response to, of tasks I began work on but haven't touched for a long time, of routine things showing up in my calendar in the coming week (to help me with planning my time and provide clarity of the expected drain of mental power in the coming days). In fact: Anything that can leave my mind while leaving me in safe confidence that it will resurface when I need it to.
The problem is: This is a crutch. And soon it will take me hours to digest the digest, leaving even less time to work and adapt new technologies.
And if I have to call for the digest, I will forget to do so. But if it show up on its own terms, it will newer show up at a good time - because there is never a good time for being distracted from what I am doing and reminded of more work!