Agile development model is also a type of Incremental model. Software is developed in incremental, rapid cycles. This results in small incremental releases with each release building on previous functionality.
Advantages- Customer satisfaction by rapid, continuous delivery of the useful softwares. People interact with each other much. Face-to-face conversation is the best form of communication. Continuous attention to technical excellence and good design.
Disadvantages- In case of some software deliverables, especially the large ones, it is difficult to assess the effort required at the beginning of the software development life cycle.
There is lack of emphasis on necessary designing and documentation.
Source: http://selenium-makeiteasy.blogspot.com