I use it for various things like reminders, alarms, and calling folks. I also use it for things like checking what games are on for the day, checking scores, standings, schedules, and finding local businesses near me. Oh and math questions like what is 15% of $4.27?
Siri is really good and people under estimate its capabilities. Researching what she can do is something many should look into. Hell, asking what movies come out this weekend is gold too!
I use Siri a lot while driving, to listen to text messages received and dictate responses or to check traffic conditions. I'll also occasionally use it around the house to do a quick lookup, especially when I don't have the hands free or the time to type a full question because I'm in the middle of something (that likely could use that answer).