Half all time spent on the internet via a mobile device is spent while the user is driving their car. That is not a total loss because 1/2 of all users is using Google Maps may be driving to your shop.
2/3 of the internet traffic on mobile devices use a standard browser allowing users to roam the internet at will. This may be good because they may be navigating to your website. However the con is they may be navigating away from your website.
How does one fix that problem? By following in the footsteps of Amazon and developing an app that will lock users into your website. Apps make buying a much easier and faster process because the user info is already loaded into the app. One click buying will foster impulse buying and making it mobile is like adding fuel to the fire.