Siri's mistake (which also applies to Cortana and Google Now) is to bet on natural language. I seriously believe natural language to be a mediocre interface, and we have the opportunity to do much better. We need to create a completely new language.
I disagree with it, but it's still interesting :)
The binary equivalent is Akinator [1]. It's big on Tinder too.
Basically, you want a language that lets you point at things you don't like. This gets converted to a need, which is then communicated to an array of agents whose job is to come up with solutions. Then enters the flow where you pick a solution (most of which come with conditions, such as completion time or cost), which then becomes a contract that feeds the timeline/calendar/task management system that drives your day to day actions. There's not a lot more to it.