Advantages:

• Customer satisfaction is main focus and  continuous development and delivery of useful software is done using this technique
• Product is developed fast and frequently delivered
• It continuously worked  on  technical excellence and good design
• Daily and close cooperation between business people and developers
• Regular adaptation to changing circumstances

Disadvantages:

• It is not useful for small development projects and for small teams, means if the product requirement is clear and if you are not going to change its functionality and UI then Agile process is not needed and also if a company has lets say 4-5 people in their team and among them 2-3 people are working on product development then also maintaining agile methodologies is not a viable option
• It requires an expert project member to take crucial decisions in the meeting
• Cost of Agile development methodology is slightly more as compared to other development methodology