Peter Bojanic composed the hymn "The Joy of XUL" praising XUL's key benefits including:

• Powerful widget markup (XML, Babe)
• Builts on proven standards (Reuse, Reuse, Reuse)
• Platform portability (Runs Anywhere)
• Splits presentation and application logic (Beyond Hairballs and Spaghetti Code)
• Easy customization, localization, or branding (Your Way or the Highway)

Selected lyrics:

XUL lets you build rich cross platform apps that can run connected or disconnected from the Internet. You can easily customize your apps with alternative text, graphics and layout to brand or localize your apps for different markets.

Dynamic application logic benefits from a UI presentation layer that is standards-based, scriptable, extensible, and distributable over the Internet.

XUL blurs the distinction between desktop apps and Internet browser apps because it combines the best of both worlds.

Full hymn at http://www.mozilla.org/projects/xul/joy-of-xul.html