After wearing the Apple watch for the last two weeks, I've noticed that my use of the iPhone is dropping. I still use it for web, apps, etc, but for mail and messages I usually use my watch or Mac. If I'm going to do a quick text or call I'll use my watch instead of pulling out my iPhone. Right now, I'd be happy with an iPhone the size of an iPod nano instead of my iPhone 6. I just don't need the screen size anymore, unless I'm bored and want to play a game. But even then, an iPhone 4 sized screen was fine for games. Would it work for everyone? Probably not right now. But in a couple of years, who knows? I've used a lot of voice interfaces over the years, and none of them are as good as Siri on the watch. It really makes the watch work.