Optional procedure. At 15 the procedure likely requires a general anesthesia (put to sleep), significant post operative pain & swelling. This procedure was one of the most popular elective surgeries during my years in the navy supposedly due to recurrent infections while working in hot areas on ship. You never develop penile cancer in the removed skin, but that is rare to begin with. Some reported decrease in std's.
Cosmetic or needed. Many 15-year-olds request circumcision because most of their friends are circ'd. There is no need for circumcision if his foreskin retracts freely without discomfort. Many boys think it cleaner to be circ'd. This is true if the boy doesn't wash under the foreskin. Incidence of aids and hpv infections in africa is lower in circ'd men. Condoms are largely protective. Penile cancer is very rare.
None. If the circumcision is not for adhesions of the foreskin to the penis (phimosis), for infection (balanitis), or for a religious conversion, why do it. There really is no "good facts". Please provide more information.