If someone wants to check their touch screen, let them turn off their phone, wait 30 seconds. Then press and hold the vol up and vol down button (2 at the same time) and connect the phone to the charger. When the Apple logo appears, release the buttons. The phone will turn on in self-test mode. Accept the terms of use, connect to your local Wi-Fi network and you can choose the touch screen test. I think that for many people this will clarify the situation whether it is the hardware or software that is faulty.
Unfortunately this test will not detect the issue I have on my launch day 16PM - input lag. But it works good to find out if any part of the touch screen is not responding to input at all.