John Gruber wrote about Siri’s improvements.
I’ve noticed over the past year that Siri is getting faster — both at parsing spoken input and returning results. I use iOS’s voice-to-text dictation feature on a near-daily basis, and it’s especially noticeable there. I’ve been using a Moto X running Android 5.0 the past few weeks, so today I did a side-by-side comparison between Siri and Android’s Google Voice Search, asking both the simple question, “What temperature is it outside?” Both phones were on the same Wi-Fi network. Siri was consistently as fast or faster. I made a video that shows them in pretty much a dead heat.
As Gruber rightly pointed out, it is not so much about whether Siri or Google Voice Search is faster, but rather a testimony of how Apple is catching up in terms of web services.