There are lots of arguments over whether or not to create a mobile version of a website or to just make a responsive design that adapts to the device it's being viewed on. If you do go for the former option please make it responsive too!
When so many people share links on social networks there is no guarantee what device someone is going to follow the link on. It can be very frustrating when you're taken to a mobile version of a site when you're using a desktop computer. In my experience, the majority of mobile websites apply no restriction on the width of the page like we tend to do with desktop aimed sites. The result is a very readable page on the small screen of a mobile; and excessively long lines of text on a full screen desktop browser that are difficult to read.
There is a simple solution: use the responsive design technique ignored in favour of the mobile site to make it adapt to the large screen. It doesn't need to be anything fancy. Just applying a maximum width on the content when the screen size increases above a certain width will suffice.
Remember responsive design works both ways!