The Wall Street Journal reported yesterday on a survey of iPhone 4S users that found that 87% use Siri at least once a month. However, the survey found that only about a third use Siri daily or almost daily to place phone calls, send text messages, or look up information. Those functions are also the most commonly used features of the iPhone. The survey found that few use it for scheduling meetings or playing music, with about a third of respondents never having used it for those functions. Overall, 55% said they were satisfied with Siri, and 9% were unsatisfied, with the rest falling somewhere in between. The biggest complaints about Siri are that it doesn't understand acccents, and it doesn't work if there's ambient noise. An good overview of the sorts of requests you can make of Siri can be found on TUAW.