I used this to reverse couple my 50mm 1.8 to my 18-55 IS. It works great and tha magnification is amazing. It did cause some significant vingetting, possably because I am also using a reducing ring to couple these two lenses. But for a real macro without spending the cash on a real macro lens this can't be beat.
Like a lot of people I keep 52mm UV filters on my 52mm lenses at all times. Mine are B&W and lens caps and other filters can screw into them. Whatever you do, if you use this ring, remove your UV filters first! The very first time I used this ring, it worked fine but got itself screwed incorrectly (lodged) into one of the two filters it was screwed into, and the two were almost impossible to separate. After about an hour I was able to get them apart, at the cost of some amount of damage to the threading of my filters and lenses and my hands, and avoid replacing the filter (which cost 5 times as much). I threw it right out and I'm getting a real macro lens, a Micro-Nikkor 105mm f/2.8.