There is no clear difference. It is two different methods to do the same thing. The advantage of @import is that it is not supported in the old browsers, so you can load a modern stylesheet without the fear of upsetting old browsers trying to render it and leave those unstyled. However, it seems that @import is executed after the page has loaded and link is executed right away. That means that with larger stylesheets, users can see the unstyled version for a split second when using @import. I don't know how many occurences of this are there or how browser independent the problem is (you will most likely spot it in IE) or even how much does @import attribute to that, so it is hard to say @import is not recommended because of that.
All that said, it is down to personal preference what you want to use. I use link.