Siri is the "personal assistant" on the iPhone 4S. If you ask, she can tell you where the nearest ice cream store is, what the weather's going to be like tomorrow, what the square root of five is, or whether or not you are fat. Also, tell her to play a song, text or call a friend, plan an appointment, or set an alarm, and she will. It's pretty amazing.
However, you must remember that Siri is essentially an inanimate object. It is all too easy to fall in love with her because of her sassy, adorable remarks. But don't make the same mistake I did. She will never love you back, and she doesn't hesitate to say so.
You: "Siri, what's the meaning of life?"
You: "I accidentally the whole bottle."
Siri: "Is that so?"
You: "Siri, suck my dick."
Siri: "Ask nice, now."