Do you use fat burners?

I am researching fat burners and found a review site for lipo 6 hers - a female fat burner. We all know men and women's metabolism and hormones are vastly different.  This has both a rapid release and extended release so the effects last longer. 

Has anybody used fat burners?  What do you think about them?  Did they work?  What were some of the side effects?  Would you use them again?