In iOS 6, Apple introduced a number of improvements to Siri such as the ability to respond to your sports, restaurants and movie related queries, give you turn-by-turn directions, open apps and update your status on Facebook and Twitter.
In iOS 7, Siri has received another overhaul. Here’s what new:
Personally I have been finding myself using Bing more and more lately with better results than Google. Perhaps Google should focus less on shoving ads in my face every 2 seconds and more on fixing their search engine. So maybe apple's move to Bing will prove to be a smart move in the long run.
It also gives you an option to search Twitter for your query below the “Did you mean” section. Tapping on Twitter displays the Tweets that match your search query within Siri’s UI.
You can also search Twitter for tweets on certain topics, or a specific user. You can ask Siri questions like “What is Twitter user saying” and it displays 10+ tweets by that Twitter user. (this could be useful)
Siri is also integrated with Wikipedia, so queries such as “Tell me about Niagara Falls”, displays information from Wikipedia within Siri’s UI. The consolation of integrating Wikipedia and web search results powered by Bing in Siri’s UI is that, it should make it a lot more easier to use Siri when the device is locked. In iOS 6, Siri had to launch Safari to display the search results, which required you to unlock the device.