Things to try with Google's Android 4.1 Voice Search
itworld.com
itworld.com
http://www.youtube.com/watch?v=kw-RzN4xYyE&feature=playe...!
I think it's highly debatable depending on what you're actually searching for, but indisputable that Google Now is quicker because it does the voice recognition locally on the device rather than having to upload it to a remote server.
It does not. It uploads to a server and does the recognition there, and it doesn't work unless you're connected to the internet. Some functionality (I'm only aware of "Call X") works if you install offline speech recognition, but nothing else.
However, it's easily the best phone I've ever owned. I much prefer it to the iPhone, too.