Siri may not be able to hold a scintillating conversation (yet) BUT he/she (depending on the voice you've set) can actually be really useful.
To activate Siri, press and hold the Home button.
After asking your first question, you must touch the Siri symbol at the bottom to let it listen for your next command. Wait for the “Beep Beep” noise to indicate it's listening.
If you can't get Siri to work, make sure Siri is enabled by going to Settings – Siri & Search – and check “Press Home for Siri” is toggled on.
Siri itself can give you tons of possibilities if you click the ?, but here are a few I use: Define a word (ie "define oligarchy"), perform a calculation (ie what's 5% of 115), perform conversions (ie "convert 10 Celcius to Fahrenheit" or "How many cups in a litre / pint?"), set an alarm or timer, set a reminder, create a calendar event, take a note, change phone settings (ie “Turn off Bluetooth”), read out or send text messages / Viber messages / emails (ie “read last email from Dad”), call contacts (including with speaker on so you can use it hands free, ie “call mom with speaker”), perform calculations and conversions (ie “convert 10C to F”), "find my nearest gas station" and then "give me directions," and even "tell me what song is playing."
You can change its voice (Settings - Siri & Search - Siri Voice). You can also teach it how to pronounce your name. Ask it “What's my name?” and when it tells you, tell it “You're pronouncing that wrong” and it will ask you how to pronounce it. You can do that with your contacts too. Ask it "Get contact info for (name)", spell it out if you have to, then when it brings up your contact's info, tell it “You're pronouncing it wrong.” It will ask how to say it, listen to what you say, and then give you options to choose the best pronunciation.
Occasionally Siri also has a sense of humour, albeit preprogrammed, as seen when you ask it “What is 0 divided by 0?” Cookie Monster is sad that there are no cookies! If you want a boggling list of options and examples for using Siri, check out this article on CNET. https://www.cnet.com/uk/how-to/the-complete-list-of-siri-commands/