Exactly what the doctor prescribes. Sufficiently but not excessively fine-grained control over what type of content a site can load from where. IMHO, much better than other, potentially more well known alternatives.
The one thing that could use better documentation is the specifics of the inheritance algorithm. Right now you have to look at the source code if you want to know how it precisely works.
Many thanks to the author indeed. Beautiful addon, conceptually, functionally and interface wise.