As a user, I'm not sure I'm impressed. On my WP8 phone, I pin a live tile to the home screen exactly where I want it, at the size I want it, and it displays the information I expect to get from it. But Google Now sounds like a live tile knockoff that's constantly changing because it's guessing what I want to see based on personal information that I agree to share with it. I don't recall this approach ever working, and it practically guarantees that it will only have information I want a
fraction of the time, so I'm unlikely to give it a prominent place on my home screen (or even use it if it affects battery life). If/when they start slipping in ads, it will be even less attractive.
But in the field of personal agents, it's definitely a significant milestone. At some point, we'll want to be able to ask what's on today's schedule when we wake up in the morning, or immediately check messages when we walk into our homes, or find out where a movie is playing and buy tickets when we hop into our self-driving cars that will take us right to the theater. Nobody's going to want to talk into a quaint little smartphone when all this becomes possible, but it's probably where personal agents start getting refined into a usable state.