I use Apple’s Siri a lot, but I’m surprised by the number of my friends that don’t use it at all. I think Siri is a lot like the first Blackberry keyboards — it’s hugely useful, but you need to stick with it a bit to get used to it.
To be clear, I rarely use Siri as the “personal assistant” that Apple highlights in their commercials. Most of my usage (90%) is straight text input (i.e. the microphone icon on the keyboard) for emails, text messages, Facebook status updates, and Google searches. For example, I’ll set up a new email through the standard touch UI, then use Siri to dictate the text body. The speech recognition is quite good, and I’ve learned to speak a little more clearly to make it even better.
For the personal assistant features, Siri is the fastest and easiest way to get meetings into my calendar. Just say, “Schedule Rob at 9am on Wednesday for an hour” and it’s done. It’s also great for dialing in the car.