Some S.E.O.'s will tell you that reciprocal linking is beneficial. Others will say that reciprocal linking has outlived its course. If you choose to trade links, here are a few things to consider.
The point of obtaining back-links is to help your search engine rank. Every link to your site is like a vote for your site. If it's a one way link, from them to you, even better! The quality of the back-link is also important. If a high ranked site like Microsoft were to link to your site, it would be considered a very important "vote," and would surely outweigh back-links from many other sites. But what if your back-link isn't real? There are website owners and directories out there who are willing and eager to trade links with you. But beware, because what they're really trying to do is create a one way link; from your site to theirs!