There are a few common complication with any plastic surgery, and fortunately we have ways of limiting the risk of these problems. Some of the complications are related to healing, which are medical in nature, and others are related to appearance, and are more aesthetic in nature.
For the healing complications, your surgeon will take many measures to reduce risks of problems such as bleeding, infection or anesthetic-related problems. Your surgeon should go over the details with you prior to surgery.
Aesthetic related implant complications can occur-- such as asymmetry, implant visibility or rippling, excessive drooping, or problems with capsule formation over time. The chance of such problems happening varies from surgeon to surgeon. I strongly believe, and there is evidence to support this, that selecting the proper size implant for the size of the patient's chest wall reduces the long-term risk of problems additional surgeries.
In my practice, as well as in other leading practices, we select the proper size implant based on the width of the chest and breast rather than only focusing on the volume in cc's. Many patients, and indeed many surgeons, are so focused on the size of an implant in cc's, that they end of placing implants that are far too wide for the overlying skin. These patients have a higher risk of drooping over time, visible rippling, asymmetry, and unnecessary revision surgeries.
Remember, you need to look great not just for a few months or a year, but for years and decades. Work with a skilled, compassionate and reputable surgeon to choose an implant that has the highest chance of both looking great and lasting safely.