In addition to preventing the reuptake of
serotonin, it also acts directly on certain
serotonin receptors in the brain (it's farily complicated and way beyond the scope of this message board) It is often grouped in with the other SSRIs, which it almost technically is, but is usually refered to as an 'atypical antidepressant' or serotonin modulator. I don't have any personal experience with it, btw. Although we are all different, it has certainly been successful for some people.