It seems too low tech to be useful for any project of any complexity. Existing HTML template frameworks do a lot of things like character and syntax aware data escaping (and avoiding double-escaping), template caching, plugins, code generation, tag extension, filters, etc.

Other than being slightly more concise and appearing more functional, I don't see the benefit of this over something like Twig or Smarty. At some point you're going to wind up re implementing features that already exist in a framework anyway.