Setup developers' biggest gripe on earlier FLEXnet InstallShield versions has been the two InstallScript issues below:

1. The need to bootstrap a scripting runtime. setup.exe != pure .msi
2. Bugs in the ISScript engine

"I am pleased to report that both of these problems are HISTORY!" says Texas-based Christopher Painter, setup engineer and blogger whose posts on "Hardcore Setup Engineering" are widely acclaimed in developer circles.

Painter calls the InstallScript design enhancements of FLEXnet InstallShield 12, "the Holy Grail of custom actions."

"Imagine all of the glory of InstallScript that gives you an integrated IDE, Compiler, Linker, Debugger, a host of functions, simplistic datatypes, and the ability to easily invoke Native Win32API, COM and Managed Code—all in one package with easy access to the MSIHANDLE," writes Painter.

Additional Info
Read more about Painter's observations on FLEXnet InstallShield 12's InstallScript enhancements. You can also find Painter's blogs @ [Feeds>>Windows Installer Blogs>>Hard Core Setup Engineering] OR Click Here.

Source: Macrovision DevLetter, August 06 Edition & Christopher Painter's Blog