Phork is released under the MIT License. This means that you can use Phork for both commercial and personal use without having to pay a licensing fee. Phork is free.
Phork is completely object oriented and uses the Model-View-Controller pattern. It's written in a very modular and flexible way. Just about all the core functionality can be extended or replaced if necessary.
Phork requires PHP 5 or greater. This means it can take advantage of all the latest and greatest features of PHP and isn't weighed down by PHP 4 backwards compatibility.
Phork is easy to install. You don't need to use the command line or run any configuration scripts. It has very minimal requirements.
Phork has a full manual with installation instructions, class definitions and examples. There are also API docs generated from the code comments, and a wiki with code snippets.
Phork promotes community involvement. There's a forum to ask questions, make suggestions and submit bugs, as well as a wiki for sharing code snippets and other useful information.