Siri doesn't always give the same answer. I had read online about a user asking, "Siri, will you marry me?", to which it replied, "I'm sorry, marriage is not covered by the end user license agreement." But when a good friend of mine asked the same question with his 4s, Siri replied, "I think we should just be friends."
On a more serious note, my friend finds himself doing a lot less typing with hisv4s than he did with his previous iPhone. Not only because of Siri, but because the 4s has decent voice recognition that can, for example, be used to dictate a text message.
According to Apple, Siri understands and can speak besides English,
French and German, and will support additional languages in 2012, including Japanese, Chinese, Korean, Italian, and Spanish. In Britain Siri becomes 'Daniel' with a British accent.