Mostly I thought [what Twig offered] were silly things that were not really needed unless you had a team of designers to work with, however, during my exploration, a couple of things occurred to me that I had not considered about templating systems before. One being the enforced separation of concerns they provide; you simply cannot do anything from inside them which you shouldn't be, keeping your presentation very very clean. The second, being that they're not all as terrible as Smarty.
He helps you get Twig installed (via PEAR chnnel) and includes the code for an application resource and the changes you'll need to make to your application.ini to get things working. He uses a base controller setup, so he shows how to introduce a "twig()" method into that to help with rendering. Finally, there's a sample class included that includes two actions, both using this "twig()" method to pas the output data through the twig interpreter and out to the view.