I don't use Siri to ask questions like they do in the Apple commercials because it doesn't work as good or fast as the Google app that does the same thing. I agree and use Siri all the time to write texts and to write things in Calendars.
I use Calendar not only for appointments but also for reminders because I sync it with Outlook on my laptop. Before I would record a message using Voice Memos app and email it to myself so when I got home I'd write it into Calendar then sync it to my iPhone. Now I just use Siri and write it down directly.