NSIS 2 makes it is possible to create installers with a custom user interface. The Modern UI is an interface with a style like the wizards of recent Windows versions. This new interface also features new pages (Welcome, Finish, Start Menu) and a description area on the components page. The interface and the graphics can be customized using the provided settings. Using the Modern UI macros and language files, writing scripts with a modern interface is easy.
For more information and documentation see the Modern UI 2 Readme.
NSIS 2.34 brought with it a new version of Modern UI - version 2. It is faster and more extendible. It allows plug-ins to add new types of pages and even change existing pages using a simple NSH file. It also uses nsDialogs which faster than its elder sibling - InstallOptions.
For more information and documentation of the old version see the Modern UI Readme.