Although I'm not a health expert, I've been using birth control for many years. The efficacy of your pills depends on your individual health and your continuous usage. The package inserts indicate several side effects, for example weight gain and spider veins, but not every user experiences these side effects. I did not gain any weight, my sister did. Inserts also indicate specific conditions that do not mesh well with birth control pills, such as if you are a smoker or if you are over 40. With certain conditions, birth control pills may exacerbate a problem or may help a problem. For example, I suffer from extremely bad migraines with aura, and for the most part doctors recommend that women like me never use birth control. However, for some types of migraines, like those related to the menstrual cycle, birth control may alleviate attacks. For some people, like me, a lower but effective dosage (I'm on the lowest possible hormone dosage that is commercially available) works better than a high dosage.
Some things you can check out if you are torn on the idea of hormonal birth control options are IUD's such as Mirena, or NuvaRing, which I believe still has some hormone in it, and there are other options for pregnancy protection like male condoms or female condoms.