We've spent some quality time with Google's new voice-enabled search and information system on Jelly Bean, Google Now. It's an interesting system that could be described as Google's take on Siri, but that's not entirely a fair description. Yes, Google Now allows you to perform searches by voice and provides a mix of pre-computed information along with web searches, but it goes further by offering persistent "cards" that automatically populate based on your searches.
The auto-population is both a blessing and a curse. When it works, it works well. For example, if you search for a location, that location will be saved as a card that you can go back to later — including the full details on the transit time. The same applies to weather, sports scores, flight times, locations, and a few more bits. Cards will also appear both inside Google Now and in your notification area when called for — like when you're standing at the bus stop and your bus is late.
The downside to this auto-populate method is that you sometimes feel as though you don't have direct control over your cards, why they appear, and how to get them back after you swipe them away. Each card had its own settings where you can choose a "priority," which in theory should help determine where the card appears in your stack. In practice, however, we'd have much preferred more direct interaction and control.
As far as voice accuracy goes, we really have nothing to complain about — it works as well as Siri at recognizing our mumbles and translating them into searchable text. With Google Now you tend to need to state your queries more directly than with Siri, which is a little more forgiving of a conversational tone. We couldn't help ourselves from testing it head-to-head with Siri and our results were mixed, actually. Siri has more depth of information in a wider variety of categories but it still has gaps — and Google was not shy about filling those precise games (like transit and flight information) with Google Now.
Overall it's a compelling, if sometimes mystifying, experience. If you are worried about Google knowing too much about you, magically appearing cards of information based on your search and location history is probably going to rub you the wrong way. On the other hand, if you're a fan of ambient, contextually-aware information, it will be right up your alley.