I've been using Google Now for a while and have found it moderately useful. However, for all the virtual intelligence it shows when it's useful it's the lack of intelligence it shows when it's not that means that - whilst I use it - I don't trust it.
The major benefit I have found is that, assuming I have an event in my diary and that event has a location that Google understands, it will give me an estimated time to get to where I need to be based on where I am. The travel times are only estimates but they I find them reliable enough that they're useful as a reminder.
I've also told it where I live and where I work so it will tell me how long it thinks it will take me to get there and when the next train is. Later in the evening it will tell me the time of the last train home.
This is all well and good especially as its information - like train timetables - that I already know well enough to be able to assess its accuracy and usefulness. Essentially I trust the information it gives me is accurate enough.
What I don't trust is it's ability to provide me with relevant information.
Whilst it's pretty good at knowing when to show "time to work" as opposed to "time to home", especially when I'm actually interested in that information, I've noticed that it does sometimes show me "time to work" in the evenings and at weekends. I know from experience that this information is accurate but it's not relevant.
When I was in Amsterdam for Mobilism (and when I had a data connection) it was consistently telling me the time to Schipohl airport and where the nearest metro station was located because that was the first step in going either home or to work. I've no doubt the information was accurate but it wasn't really relevant.
The event that triggered this blog post was last night. I was sat at home and noticed it was telling me that the last bus home was in five minutes from the bus stop at the end of my road. This was a particularly bad failure of the virtual intelligence: it knows I'm at home and I know it knows because it can geo-locate me exactly in my house when I'm on my home WiFi connection. It also knows that the nearest bus stop is at the end of my road and it will take me two minutes to walk there (I walk faster than it estimates but I know it's consistent so can adjust). It also knows the time of the last bus from that stop, and again that's information I can easily verify. The issue is that, for all the accuracy of this information, it's not relevant to me and it should have enough information to figure that out.
This isn't a criticism of Google Now - it generally does a good job with the information it has available. This is an illustration of just how hard it is to solve problems like context and relevancy.
At half past eight this evening, whilst at a friends' house, Google Now had decided the most relevant information was "time to work" rather than "time to home". Accurate but not relevant.