Over the past several weeks Siri use has become more and more difficult. She doesn't hear me some times - sometimes after pressing the button I have to say Hey Siri to get her attention - sometimes after making requests she gives me a list of things I can ask her in general. It getting very frustrating.
Did you reboot the phone? Press and hold the top power button until a turn off slide comes up. Turn off. Wait a minute and then press same button again to turn on.