Advantages: 1. You can use one name for similar objects and save then with the same name but different indexes. 2. Arrays are very useful when you are working with sequances of the same kind of data (similar to the first point but has a different meaning). 3. Arrays use reference type and so.
Disadvantages: 1. Sometimes it's not easy to operate with many index arrays. 2. C environment doesn't have checking machism for array sizes. 3. An array uses reference mechanism to work with memory which can cause unstable behaviour of operating system (unless special methods were created to prevent it) and often even "blus screen" and so on.