It is unbelievable how many websites are not designed for use on a mobile device.
i have recently tested the functionality of different sites using a variety of devices. While using a mobile phone, pop up pages may be blocked which gives the impression the selection is unavailable. Sites where you have to register - an absolute nightmare. Ordering online somewhat tricky, if at all possible. Websites tend to fare far better on an iPad or tablet.
With more and more business being conducted "on the go", regular testing should occur to protect your brand and secure sales.
I would be interested in others opinions and personal experiences.