Its emphasis on simplicity and minimalism caught my eye and I decided to give it a whirl.
3 months later, I have to admin I'm a total fan. It makes the simple stuff easy, and the tough stuff.. well.. possible. It is a pure view-controller framework w/o ORM. Perfect because my backend is usually handled by Solr anyway.
Highly recommended if you're not already invested in Zend or one of the biggies (cakephp, symfony, etc)