Cortana has been in Alpha, for India, and it almost feels like forever. The only way to get Cortana outside US was to set language and speed to UK and get it working. Good news is that for Windows 10 Mobile has enabled Cortana for India and there is no need to change anything. You can keep your country, speech and language all same and still have Cortana working exactly like it had worked for US.
Using Cortana you will be able to do lot many things now. For example, Go to Cortana, Tap the hamburger menu and select Notebook. Now select Eat and Drink and here you can configure price range, cuisine preferences, and how far you are willing to go. That way, Cortana can recommend you places to eat out based on your current location. It also picks up recommendations from Foursquare. There are many similar cards that you can make use of.
Also notice few more things that will come out with final roll out of Windows 10 Mobile which includes option to send SMS from Desktop, get missed call notifications, and so on. Cortana also has option to connect accounts like Linked In, Office 365 and Xbox Live. So if you connect to Xbox Live, you will be able to get insights about your gaming activity and relevant content.