Screenshot of speech to text activation found in iOS 5 beta 5 hidden keyboard

I'm really looking forward to the new, system-wide "Assistant" voice control system Apple's rumored to be including in iOS 5. From the leaks, it looks like it might be implemented similar to Android -- a microphone button on the keyboard that you press to tell your iPhone or iPad you want to talk to it, then it takes your voice command or text entry, sends it to Apple's servers, and either does what you told it to do or types the text you told it to type.

Currently iOS takes very simple commands like "call" or "play"... and I almost never use it. Holding down the home button for a few seconds then waiting for it to beep and be ready just seems... slow. I'm not sure if the microphone button will be any better, honestly. Now if Apple figured out some way for it to be quietly waiting for a special code phrase that I could say to make it wake up and start listening, that would be sweet, but the technology, especially the impact on battery life, probably isn't there yet.

It should at least be far more functional that the current system. With Apple's purchase of Siri and the rumors of their Nuance (the makers of Dragon Dictation) deal, I expect I'll be able to do much more, like:

"iPhone, get me a taxi at the corner of Sherbrooke and Crescent." "iPad, make me a dinner reservation at Gibby's at 8pm tomorrow." "iPod touch, take a note -- bug Seth on the podcast tonight. So say we all."

Will it work well enough and smoothly enough that I'll actually use it? That I don't know.

What are you looking for in iOS 5 "Assistant"? Would something like Android's existing implementation be enough? What's your realistic assessment of what Apple can deliver, and what's your totally unrealistic hope?