In terms of supplying basic facts, Siri shines, combining accurate responses with cards that offer deeper information dives, especially when the assistant taps online math engine Wolfram Alpha for its answers.
When you ask more complicated questions, Siri often defaults to a list of search results. We didn't ding any of the assistants more than a point if the answer was readily apparent from the list of responses. But when more complicated, interpretive questions were asked--"How long does it take light to travel to the Earth from the Sun?"--Siri failed to provide any sort of coherent result.
Perhaps it was too much to ask for Siri to play a song we didn't own in iTunes, but its ability to handle common tasks also lacked sophistication. For example, Siri lacks geofencing capabilities, so asking it to remind me to buy eggs and milk at the grocery store set up a generic reminder, rather than keying it to a specific location, as other services do.
On the other hand, Macworld goes into several things Siri does do that other services don't: Utter "Read me my email," and Siri will comply. Say "Turn on Bluetooth," and Siri dives into the settings menu. Ask her "What's going on," and she lists trending topics on Twitter.
Siri's greatest weakness is that she does what you tell her to do, and little more. Siri's good at pinging you with reminders you set, but she won't step in to remind you that your flight is late. In fact, if you don't say "Tell me about Southwest flight 212," the list of search results it generates simply includes the Southwest webpage. On the other hand, iOS apps can step in. YouTube, for example, pinged me about a new video I might be interested in when I rebooted the iPhone. And Siri can post to Twitter and Facebook.
If you're unimpressed with Siri, you can explore alternative digital assistants for iOS: Cue and EasilyDo, among others. You can also install Google Search, which hides the third--and best--digital assistant, Google Now. Yes, if you do think Siri sucks, you can actually download a superior digital assistant, Google Now, directly to your iPhone.
Google Now: Still the best
Google Now launched with Android 4.1 in July of 2012, and the software has only improved with age. Google has broadened its reach, from tracking packages to providing travel reminders. Google doesn't thrust itself into your face. If anything, you sometimes need to dig a bit to find all it has to offer.
And that's Google's strength: Google Now virtually invented proactive notifications. In general, what you need is pretty close to your fingertips, when you actually need it.
Sign up for CIO Asia eNewsletters.