If you tell Siri "Do not disturb," it understands that you're alluding to the new feature in iOS 6 to mute alerts and notifications, but it can't enable that feature for you: Instead, it will helpfully provide a link to that setting.
Which is to admit that, as helpful as Siri is, I still have plenty of items on my Siri wish list that it hasn't learned to handle. For example, you can't use Siri to add or edit contacts, to go directly to specific websites, or to explicitly control third-party apps. And Siri still can't toggle settings like Bluetooth.
As mentioned above, Siri flails when you try to ask about athletes or movie stars with unusual names it can't transcribe. And its information is generally only as good as its providers can offer.
When Siri understands you on the first try, and when its answers are accurate, it's awesome, and indistinguishable from magic. When it needs multiple tries to understand you, or when its answers are no good, Siri brings back unpleasant Newton memories.
That said, with Siri's gains in iOS 6--not to mention back-end improvements that seem to have Siri understanding me better than ever--it has become an even more indispensable way for me to interact with my iOS devices. Despite its occasional shortcomings, I'm grateful that it's there.
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