The effect of circumcision on reducing the risk of AIDS, particularly in Africa, is as well established as any other public health measure.

http://www.who.int/hiv/topics/malecircumcision/en/

http://www.cdc.gov/hiv/prevention/research/malecircumcision/

http://science.howstuffworks.com/environmental/life/cellular-microscopic/circum-aids.htm

http://www.aidsmeds.com/articles/VMMC_Proof_1667_24496.shtml

That isn't to say it has anything else going for it, but that consequence is important. Particularly in Africa where the AIDS risk is astronomical, and despite what Eliza says, circumcision rates range regionally from "almost everyone" to "almost nobody".

http://en.wikipedia.org/wiki/Prevalence_of_circumcision