..the document-centric model was never allowed to bloom as we had hoped, to the point where it would differentiate the Mac user experience.
Personally, I feel that nowadays the Mac's obviously application-centric interface (the dock, application-global menus, etc) is the thing that sets it apart from (and above) Windows' more fluffy 'some documents, some apps' attitude.
I prefer it because it's more honest as to how the system actually works. Running applications use memory. They take time to start. So a document-based system behaves differently when opening the first document of a give type vs the second document of that type, or closing the last open document of a particular type vs closing any other document.