This is great for people who don't want to be tied down with taking a
pill at the same time every day,
but:
It isn't as
physiological (some have spotting; no period every N days)
It of course doesn't protect you from whatever
STDs your partner(s) might have (including
HPV, which causes
cervical cancer).
Towards that end, see condom, dental dam, and masturbation.