Endless "Would you like me to search the web for...?", that was what my experience was.
When Apple came back with iPhone 4S, the hardware had little advancements. Instead, it boasted Siri as the main "revolutionary" feature. I never had an iPhone, so I only watched some YouTube videos or tested Siri only briefly using other people's iPhone 4S.
Like everyone else, I began with questions like "Weather" or "What time is it?" or "Make an appointment at 6 PM tomorrow." For these questions Siri worked very well thought quite slower than Google Now. This must be relatively easy for Apple to make Siri to respond to questions/commands that Apple engineers expected.
But when you try to ask more advanced questions that Apple engineers did not expect, most of the time you will end up with "Would you like me to search the web...?". See the screenshot above. I heard the "Would you like to search" so many times, I asked why it was so difficult to talk with Siri, in a frustration. And to put salt on my wound, Siri answered to it with "Would you like to search...".
Google Now came after Siri, but Google's Android had voice command and voice dictation far better than those of iPhone 4's. They were very useful for me. Google Now answers to basic questions using Google's vast amount of data, and when it cannot know the short answer, it just quietly shows the web search, thus saving my time.
Siri seems not to understand questions that Apple engineers manually have programed for. Yes, Siri answers to advanced questions "What is the meaning of life?", but those were so common that Apple engineers must have put predefined answers, and Siri just plays randomly one of the answers. Otherwise, why does Siri give the same 2~3 answers always?
This is a little bit different thing, but Siri's voice is too unnatural. Google Now's voice is far more natural and pleasing to hear. Siri's voice is pain in the ears. Though the graphical elements in the answers are quite pretty.
The bottom line, Siri is too much hyped by the wonderful marketing ability of Apple. Siri can only
- Answer/execute very common tasks and questions relating weather, appointments, launching apps, etc (they show the list, if you press the (i) button.)
- Answers to questions in a format, which Apple engineers had predicted, by using the data from Wolfram Alpha.
- Answers to some silly questions/jokes that Apple engineers had input pre-defined answers.
- All others, "Would you like to search the Internet".
Unless you want to spend your free time on listening some silly jokes from Siri, Google Now is far more fast and pleasing to use.