Having a mobile site is important. But even more important is having a mobile site that customers actually want to use.
As more and more people purchase smartphones, more of your customers will start using them to make purchases. And nothing will turn them off more than a mobile site that is confusing and offers a bad customer shopping experience.
Mobile commerce is still new. And many people have experienced problems when trying to use mobile sites. But people are not patient. If they can't purchase your product on your mobile site, they may simply never return.
It's essential that you focus on customer service in all areas including mobile. And with mobile, it means that you have really only one chance to get it right.