I'm genuinely curious to see how often Siri is used, and in what contexts.

Not to be cynical, but to re-calibrate my barometer. The only person I know who uses it is my partner's nine year old daughter, and even then not often.

Sometimes I accidentally use it to search for directions, then switch to Google's voice interface when it (inevitably) fails and I realize what I've done.

I don't like the errors voice messaging causes (you can tell when someone's sending texts with it), so I never use that.

It's OK for setting alarms or timers but I've only done that a couple times because I always forget about it and do it manually instead, or (for timers) my phone's farther away than a microwave or something.

Tried using it to record notes by voice once. It was entirely terrible at that task.

My phone would be at most 1% worse if Siri were simply gone.

You use a microwave as a timer? :)

All the ones I've had have a timer mode that doesn't run the microwave itself. Handy when you need to time something in the oven and something on the stovetop.

I have an Apple Watch and I use Siri multiple times daily. Most frequently to set timers, but sending iMessages to friends and family is a close second. I also frequently use Siri to control music while I'm washing dishes or my hands are otherwise busy. If there's a faster way to skip a track when my hands are soapy, I don't know of it.

Also, FWIW, I've gotten pretty good at discreetly talking to my wrist in public. In any moderately loud area I don't think anyone even notices me doing it.

That's one of the reasons I'm looking forward to AirPods. I can use Siri with the earbuds I have, but their microphones are crummy enough to require I do so somewhat loudly. While I don't always mind seeming like I'm talking to myself in public, and indeed there's the odd occasion when seeming unpredictable and potentially dangerous can be positively beneficial, having the option of greater discretion would be nice as well.

I frequently use Siri to create reminders during my commute, because it's more convenient than pulling my phone out (especially in winter!) and I almost always have an earbud in anyway. If a quicker, lower-friction method exists of capturing stray thoughts before they get away, I haven't found it yet.

I also occasionally use it when I wake up in the middle of the night and don't want to abuse myself with a bright phone display in order to find out what time it is - I don't keep a clock on my bed table, but my phone always charges there. "Hey Siri, what time is it?" is handy in that circumstance, unless the "Hey Siri" part decides not to trigger, which happens often enough that I don't really find it reliable. (I think that must be because a half-asleep voice sounds different; this isn't a problem I generally have at other times, even when using a $15 Bluetooth earbud which can't possibly have a very high-quality microphone.)

I plan to use them as a remote interface to my iPhone, especially when at home (iPhone lives in a drawer while charging). Things like setting timers, creating reminders or let Siri read out received messages - basically what Echo does, but not bound to one room. "Hey Siri" does not really work for me, I stopped using it almost completely.

I and my parents use it all the time. setting timers, directions (Apple Maps is inferior to Google maps but is often good enough e.g. "take me home"), call folks, basic operations is often easier with Siri than unlocking the phone - esp. if you have a BT headset and the iPhone is in the bag or on your table.

My most used:

"Set an timer for 5 minutes" is very handy.

"Open auto lock settings" etc gets you to nested prefs screens quickly.

"Remind me to..." for adding things to my OmniFocus inbox.