Pros and Cons of Birth Control

Samantha
Other than the protecting against pregnancy can someone tell me what the benefits and cons of going on Birth control? 
I'm going to speak to my doctor about it on Monday but I want to be well informed before going in. 
Incase it helps I'm a 17 (18 in May) female who has been diagnosed with cysts on my ouveries (i think that's how it's spelt lol)