There are following advantages of ASP.NET MVC over Web Forms (ASP.NET):
Separation of concern – MVC design pattern divides the ASP.NET MVC application into three main aspects Model, View and Controller which make it easier to manage the application complexity.
TDD – The MVC framework brings better support to test-driven development.
Extensible and pluggable – MVC framework components were designed to be pluggable and extensible and therefore can be replaced or customized easier then Web Forms.
Full control over application behaviour – MVC framework doesn’t use View State or server based forms like Web Forms. This gives the application developer more control over the behaviors of the application and also reduces the bandwidth of requests to the server.
ASP.NET features are supported – MVC framework is built on top of ASP.NET and therefore can use most of the features that ASP.NET include such as the providers architecture, authentication and authorization scenarios, membership and roles, caching, session and more. URL routing mechanism – MVC framework supports a powerful URL routing mechanism that helps to build a more comprehensible and searchable URLs in your application. This mechanism helps to the application to be more addressable from the eyes of search engines and clients and can help in search engine optimization.