Recently, Google added voice-enhanced search to its iOS search app. At that time, a lot of people started comparing Siri search results with Google, missing a major point about what Siri is and what it does.
There's a reason Apple calls Siri a "virtual assistant." It helps you add reminders, create appointments and book tables as well as search for movie reviews and look up sports scores.
The people who know and love Siri on iOS use it as a digital concierge. "Wake me at 7:15 tomorrow" and "Remind me to buy milk when I get to Albertsons" are features that go way beyond simple searches. To be fair, Google offers similar capabilities on Android but these are not available in the iOS search app, and were not really part of the discussions when that app launched.
Concierge features create ways to interact with your computer that bypass keyboard and mouse. They integrate with the underlying OS to activate user-requested functionality. A concierge transforms your intent into system actions, not just producing strings of text (as with dictation) or web information (as with search).
In OS X Mountain Lion, dictation arrived on the desktop along with reminders, iCloud-powered notes and other iOS-inspired features. What didn't arrive was Siri itself. Although all the trappings were there, the connection between voice and action didn't make the cut.
It takes a reasonably major engineering effort to connect a voice-based assistant to OS features. Why doesn't Mountain Lion doesn't currently support Siri? Apple might have run out of time, felt it wasn't a priority, wanted to test it first among a committed user base before moving it to new platforms, wasn't convinced desktop users should be speaking to their computers, or had a million other reasons why.
Siri has had a pretty bad rap as a "failed feature" among pundits. To see examples, do a Google search for "Siri and disappointment". You wouldn't know that, though, from Apple's recent advertising campaigns, which put it out front and center as a shiny selling point for iPhones.
As a committed user of the service, I personally love it. I regularly use Siri while cooking ("Start a timer for 5 minutes"), for managing my kids ("Add yellow pencils to my school supply list"), for texting ("Message Steve I need those chapter review files 10 minutes ago"), and more. I'd like to see its capabilities expand even further.
For me, Siri is fast and efficient. I get stuff done quickly with my voice without having to step through a lot of intermediate effort. That's a big reason I'd like to see it jump to OS X.
Already, I use dictation a lot more than I ever expected to -- and I'm a really fast typist, so it's not just about overcoming mechanical issues. Adding voice has helped me multitask a lot better. I can keep doing whatever I'm in the middle of, switch over to IRC for example, and dictate a response to an ongoing chat conversation and hop back.
Adding Siri would make that even better. I'd be able to shoot off messages, look up phone numbers and more, all from a central interface that doesn't require any significant task switching. How can that not be a win for users?
Many of the ways you use Siri on the iPhone and iOS device family transfer directly to the Mac. "Siri, Google a recipe for lamb and garlic." "Siri, where can I get my bicycle fixed?" "Siri, is Prometheus any good?" Just because you're on a desktop doesn't mean Siri cannot help.
Will Siri show up in OS X 10.9? I'd certainly like it to and I don't see many technological issues standing in the way. Should it be in the next iteration of OS X? Absolutely.