It's all in the execution. If all the QR code does is send you to a PDF file of the printed version, without any text reflow or responsiveness to the screen size then I agree, it's a terrible experience.
If it points to a website properly designed for multiple screen size, and the WiFi works well without too many hassle or a mandatory invasion of privacy (login to Facebbok to access the WiFi network? No thank you), then it can be a great experience. The restaurant should make sure to have at least a couple of printed copies in case someone can't use their phone, if there's a website outage, etc.