Well it prevents pregnancy, that's obvious. But if you made sure the both of you are std-free, it could replace a condom if you dislike using that. but ONLY if you're absolutely sure neither of you have any diseases.
The method of administration is non-invasive and least likely to harm the patient simply through process of adminsitration -- always a good thing.
Meds adminstered PO reach the desired plasma...
probably the most popular is yasmin. the reason being that it does not lead to weightgain as so many others do. see more details on all the popular ones here: http://www.oral-contraceptives.info