We've seen a really impressive, albeit polished, video look at Siri working on the iPhone 4S already but this video is a little more thorough and a lot more real life-ish. She's still impressively smart but she's not perfect.
When asked "What's your name?", she responded "My name is Siri. But you knew that already". To "How old are you?" she (creepily) responds, "I am not allowed to answer that question." Are you going to bust Chris Hansen on me Siri! She can do funny too, when the person said "I love you" to Siri (which I'm sure she, or it, will hear a lot), she hilariously responds, "I hope you don't say that to those other mobile phones, [NAME]".
But she's not perfect, her voice is verrrrry missy robota and she can't always understand the off the wall questions, like when asked "Can we be friends?" Siri responds, "Sorry. I don't understand, "Can we be friends". What's there to not understand, HMM!?
Take a look at the whole video though, beyond the silly question and answer game, Siri shows off her amazing breadth of knowledge and potential usefulness. I'm not sure I'll ever use Siri but color me impressed. [Apple Master Touch via MacRumors]