Visual Studio Enterprise 2015 is an integrated, end-to-end solution for teams of any size with demanding quality and scale needs that require comprehensive tools and services for defining, building and managing complex enterprise applications and solutions targeting Microsoft’s full Enterprise platform as well as cross-platform technologies.

It is recommended that you sign in using the Microsoft account associated with your active MSDN subscription in order to unlock Visual Studio. By signing in, your IDE settings will sync across devices, and you can connect to online developer services. Some customers may also have access to product keys which can be used to unlock Visual Studio.

VS Release Notes
TFS Release Notes
VS Known Issues
System Requirements
Compatibility