In addition to it's overwhelming speed I'd like to point out that Text::Xslate throws largely useful error messages on screen in case something is wrong with the markup.
Secondly, the idea of cascading templates (similar to TDL - Djangos Template Language) and blocks than can be nested and overloaded really help to build a clean view in web apps: One specifies the outer tepmlate *WITHIN* the template itself, as opposed to Template Toolkit and others that want this as a redering parameter.
To sum it up: It's speedy, has great error messages and supports template inheritance.
This is THE FASTEST template engine around. My personal test results match with Sam Graham's Perl Template Roundup. I give Xslate a big thumbs up not only because of the speed but also because of the features like object oriented syntax, Perl function API and Template Toolkit migration path.
Although I usually oppose reinventing the wheel, I make an exception for such suitable authors as could make a worthwhile module. This module author, Goro Fuji, is one of them. The module is extraordinarily fast, and yet the syntax of a template by means of using the module is never a burden on even the designers out of the picture.
I'd like to recommend the module for all!