What are the main disadvantages of Java Server Faces 2.0?

Question

Yesterday I saw a presentation on Java Server Faces 2.0 which looked truly impressive, even though I am currently a happy ASP.NET MVC / jQuery developer. What I liked most a

Answer 1

JSF has only one disadvantage: before starting "JSF" development you should clearly understand web development, core java and front-end architecture.

Nowadays "new" JavaScript frameworks just try to copy/paste "JSF" component-based model.