1. Setting location-based alerts using Find My Friends. Saying "tell me when my wife leaves work" is effective, convenient, and about twenty times faster than setting up the alert by hand.
2. Again with Find My Friends, finding out where people are. If I'm meeting somebody I can just ask, "Where's Bob?" and it shows me, so I know if they're running late or whatever.
3. Setting reminders, especially location-based reminders. As I'm walking along, I suddenly remember that I need to fix the windshield wipers on my car or something. "Remind me to fix the windshield wipers when I get home", and done. Again, way faster than setting this up by hand.
4. Quick text messages while on the go. It can both read an incoming message and write a reply. Faster than typing a reply, usually.
5. Setting timers and alarms. Put a pizza in the oven, then "timer, 15 minutes", and I get an alert when it's done.
I don't think the article is wrong, but it's a bit narrow. It concentrates entirely on search, and I agree that Siri is pretty weak with that. But Siri is good at doing stuff, at least certain stuff, on your behalf. Google's voice search can't do this on iOS at all, and my understanding is that even on Android its capabilities are much more limited.
Siri is probably over-hyped by Apple, but i personally still find it to be quite useful. It's not the all-powerful personal answer-machine that some people want it to be, but it's a handy alternate UI for many of the phone's functions.