As we have JSP and Servlet then what is need of Struts2? Struts2 have many more benefits rather than it is server side MVC-2 implementation .So that today struts is used into web based enterprise applications. Today Struts2 is used with Spring and Hibernate to make our web based application secure and faster. Today Struts2 used in project for telecom, e-Learning and banking/finance domain etc.

 Struts2 framework is more efficient than other framework like Spring web MVC, JavaServer Faces and Hibernate etc.
Struts2 As a developer point of view:- As a developer point of view a developer must have focus on there core skill area. Like a GUI developer wants to work on GUI as their skill set.But a business logic developer never wants to write code for GUI he/she wants code for business logics. Similarly a security and traffic control programmer want to focus on controller. As Struts2 is serer-side implementations of MVC-2 .So it offers clear separations between model, view and controller.
Due to clear layer of MVC model,  struts2 reduced of developers time and costs.
Struts2 as a maintains point of view Maintains in easy and have less cost in case of struts.
The Struts2 is not only thread-safe but thread-dependent (instantiates each Action once and allows other requests to be threaded through the original object).
The Struts2 tag libraries provide general-purpose functionality.
ActionForm beans minimize subclass code and shorten subclass hierarchies.
The Struts2 is neutral model and easier integrated with other framework like Struts2 with Hibernate, Struts2 with Spring web MCV, and Struts2 with JSF.
The Struts2 are lightweight (5 core packages, 5 tag libraries) and its components are reusable by the application.
 


Struts 1.3 Tutorial and Example
Spring 2.5 Tutorial and Example
Spring 2.5 MVC Tutorial
Spring 2.5 MVC Example