Download: http://www.jrsoftware.org/isdl.php
For the complete list of what's new/changed, see: http://www.jrsoftware.org/files/is5-whatsnew.htm
The QuickStart Pack now offers to download and install InnoIDE instead of ISTool. InnoIDE is a new easy to use Inno Setup Script editor by Graham Murt and meant as a replacement of the standard Compiler IDE that comes with Inno Setup. Using InnoIDE is especially recommended for new users. Note: unlike ISTool, InnoIDE supports Unicode scripts.
See http://www.innoide.org/ for more information.