While it's not perfect, Siri has done one majorly great thing for me. I can use an iPhone in a car totally handsfree (except for pressing the button to activate Siri).
Get in car (with bluetooth stereo integration that has an OEM mic in the car)
"Play songs from Rush" (Ding da ding ding ding da da...)
I'm driving down the street and I hear the text chime
"Read me my last text"
Siri reads a text from Chris "Hey are you around this eve?"
"Reply to Chris, tell him I will be home in 20 minutes"
(Siri reads it back and asks me if I want to send)
"Yes"
then
"Call my wife"
Siri calls my wife
"Honey I'll be home in 20 minutes and Chris is stopping by to help moving that big dresser."
This is a daily occurrence for me. I don't get why people can't use Siri effectively.
Here's a tip. Talk like a midwesterner (in the US version)
Wahter not warter
Cahl not cawl
I also talk to a lot of people who English is their second language (Germans in particular), so I talk to Siri the same way, very small fleeting pauses with each word, not so much that it sounds ridiculous, but just enough to notice it.
If you want a digital assistant that can do everything, well keep reading science fiction for now. When they talk back and question your motives, you'll wish they were as basic as Siri!