Siri can be quite useful, but if you really want a "Jarvis" kind of experience, like Tony Stark in Iron Man, you need to be able to interact with Siri without touching a button. Fortunately, iOS 8 makes this possible.
There is an iOS 8 setting that allows Siri to listen for the command "Hey Siri." To enable this, go to Settings>General>Siri and toggle the Allow "Hey Siri" switch on.
It's not quite as powerful as Iron Man's artificial intelligence system; you have to ask your question right after getting Siri's attention. For example, saying, "Hey Siri, what is the temperature" works, but saying, "Hey Siri," and then waiting for a response will only bring up the traditional Siri interface.
Fortunately, there's a way around this. Instead of tethering your iPhone to a wall, use a battery case. As far as the iPhone knows, it's plugged into A/C power, but you can still be mobile. Right now, I've only been able to do this with an iPhone 5s, as I'm still waiting for a battery case for my new iPhone 6, but this could be a way to give you the best of both worlds.
