What are the most prominent advantages and disadvantages of building applications using the ionic framework?

The most obvious advantages are:

Ionic framework builds hybrid applications using web technologies. It means web developers can easily build mobile applications too. Also, because it uses JavaScript, almost the same codebase can be used to build both iOS and Android applications.
Development cost is less compared to native iOS and Android applications. Ionic framework is excellent for quick application ideas prototyping.

Some of the disadvantages are:

It is not suited for high-end graphics dependent applications or games. Performances are not as good as native applications, namely animations, scrolling, and network operations.

As mentioned, JavaScript animations are not as performant as native animations. However, there are JavaScript libraries, like tweenMAX, which provide decent animation performance on the devices.