Advantages Weight is a lot lighter. Strength is stronger per pound than steel Form abilityy. Can be shaped to any contour. This means aircraft will not need any rivets sticking out which would cause drag. As above note there is less drag with composites because it can be molded with very smooth lines. Less parts. Longer life. Composites have a longer life expectancy than steel or aluminum. Add these all up together and you have a sleek, fast and very efficient airframe. The main disadvantage is cost. Each part has to be formed on or in a mold and layered and baked while in vacuummm. So it takes more time to make but the advantages outweigh the cost. You can have an aircraft that operates at $45 dollars an hour flying at 150 knots cruise or a cheaper aircraft that operates at $90 dollars per hour at 120 knots cruise with a lot more maintenance.