In response to this previous post from Jeff Moore, Tobias Schlitt shares some of his own comments on the subject - mainly that he wholeheartedly agrees.

The usage of interceptors (__get()/__set()/__isset()/__call()) makes your API a lot more readable and comfortable, while maintaining the purpose behind getters and setters: Checking the correctness of values assigned to a property and wrapping around retrieval mechanisms for a property. I personally call the way of maintaining value-correctness for properties through interceptors virtual properties, which fits quite nice I think.

Tobias gives an example of what he means by these "virtual properties" with an illustration from something widely used on the eZ Components libraries - comparing one method of setting text to an object to another (just setting versus the wrappers).