The nitty gritty details:
- MVC-based (though OFF doesn't do the model part for you)
- Enables you to use PHP directly in your templates with variables set up by your controller
- Is configurable
- Supports altering headers and serving binary files
- Does not limit you - you can add as many 3rd party PHP libs as you wish
- No scaffolding. Ever.
- Can be used as a simple include script / templating engine.