Yesterday, I had a meeting at 8:30pm that was about 30 minutes away. Before the meeting, I received a notification on my phone that told me I needed to leave at 7:37 in order to be on time for the meeting. Lo and behold, with the traffic that Google Now saw and calculated, that turned out to be true. I left at 7:37 exactly (because I was curious how accurate it would be), and sure enough I got to my destination at about 8:25. I initially intended on leaving around 7:50 or 7:55 since it was only a 30 minute drive and rush hour is over at that point, but had I done that, I would have been late. Thanks to the heads up given by Google Now, I was on time. In my opinion, that's what sets Google Now apart. I didn't have to be actively using it for it be useful. Other things out there like Siri, are only useful when I'm actively using it. So if I'm not using Siri, it's of no use to me, whereas even though I wasn't using Google Now, it still wound up being useful for me.