Analyst Gene Munster has issued the latest in his series of scoring Siri’s reliability, and his findings show that Apple continues to improve the service. These improvements are happening slowly, and not without their own setbacks, but it should come as no surprise that the service is being tweaked for accuracy. Apple is actively reducing their reliance on Google, and Siri now relies primarily upon Bing, Wikipedia, and Wolfram Alpha for the results that it shares under iOS 7.
I have personally not noticed much improvement with Siri under iOS 7, though I also haven’t been actively using it. To be fair, I find both Siri and Google’s voice efforts to be more trouble than they are worth. The only exception comes when driving, when such voice capabilities are important. In this scenario, I actually find Siri to be more accurate and easy to use than Google Now on Android.