QR codes work fine where I live. I believe problems are due to the implementation, not with the concept. I find it very convenient. Connect to the local wifi, there's no confirmation code, just open wifi (most of the time - some of them have an unnecessary "accept" step. Never any "confirmation code"). Scan. Browse. Choose. Pay, or pay later (convenient, I can adjust the tip before I pay). All in all it's much faster…
To each their own, but that sounds less enjoyable than a traditional restaurant experience to me. As you say in your example, so much depends on the "implementation" in this case too — i.e. is the service at the restaurant good or not — but a talented waiter brings a lot to the table in more ways than one.
Some restaurants live and die by their ambiance. But others the main draw is the food and/or the price and/or the speed. In that case, I would enjoy having a QR code order option.