Both. Main risk with contact lens wear is an eye infection / cornea ulcer, however it can also cause irritation, dryness, allergic reactions, etc. Advantages of contacts = cosmetic, avoiding glasses problems or distortions at high powers, and depending on astigmatism, vision with contacts may even be better than what can be corrected with glasses.
Many pros! Full vision without glasses: no fogging, heavy lenses, good peripheral vision etc. The drawbacks? They need daily care and there is always the risk of infection or other complications. If you take care of your lenses regularly, you should do great!