It is going to be a week now since the new iPhones made their way into the hands of their customers. Like with every new major phone release, some iPhone 6s and iPhone 6s Plus customers are facing some hardware problems with the device.
The bugs vary from 3D Touch not working inside Safari to allow one to peek into web pages to audio getting distorted through the speaker while playing back notification sound. Both these issues are likely software issues that will be fixed by Apple in a future update. A temporarily solution to these problems include resetting the iPhone for the time being.
A more widespread issue is the Home button getting abnormally hot on the iPhone 6s and iPhone 6s Plus. The home button on the new iPhones integrate the second generation Touch ID sensor that is capable of scanning your fingerprint almost in an instant. Users on Apple support forums are complaining that the home button gets too hot to touch suddenly. The solution to this problem is pretty simple: press and hold the Power and Home buttons for 10 seconds to reset the device. Other users report that restarting the phone also fixed the issue on their iPhone.
A small bunch of iPhone 6s owners are also reporting that their device randomly switches off, even though it has enough battery power. Another section of iPhone 6s owners are reporting that their device randomly loses network connection, and is only able to receive calls and texts once the device is rebooted. No reported workaround to this problem has been found until now, but reseting the iPhone will most likely help alleviate the issue.
All the above issues are not widespread, but still more than a handful of users are facing them with their new iPhone. Almost all of them are related to software though, so expect Apple to fix them in iOS 9.0.2 or iOS 9.1. update.