I've played with Siri, Google Now, Sherpa and others around. I like the idea of a digital secretary who reminds me of things and helps me to find information. Only the existing apps are far from it.
The reasons are also because developers do not understand us people. Google Now is essentially limited to travel, sports and news - and calendar entries. Above all, travel is overrated, as if the majority of people boards a plane every day or has appointments outside the office.
What a digital assistant has to do is remind me of things I forget. For example, to go to the gym. To water the garden. Healthy eating. To buy flowers. The important things I have in my head. The fact that Google Now shows the gate at the airport is great, but that is either on my boarding pass at the airport or on a board.
Maybe it's because I'm now house man, who, you believe it or not, has a lot of tasks that are quickly forgotten. Dusting, washing clothes, shopping, all things which I will make more or less every day, but I forget sometimes because something has come up.
I think digital assistants need to put much more emphasis on tasks and what we really do on that. It should read the Facebook status to know when I like to drink coffee, where I exercise, etc. The data are available, they just need to be brought together. (Google has not made it to today to build a decent task app and integrate)
One possibility would be that you create a list of tasks, which serves as the basis for the wizard, as we do it in the office with a secretary (e.g. department heads report every Monday). And then you have the app to know your habits, read and understand check-ins and activities. Maybe you can also use hashtags to feed them.
If that were all already possible, I would not have to buy milk today, because I forgot it yesterday.