The latter. (Expectations oow)
SharePoint is a document respository system, whereas you can add additional info (fields) pertaining to the file. That's the value add.
Once that file is out of SharePoint, it's just a Clark Kent file, not a SharePoint Superman File.
It doesn't take the fields with it, and they're not written into the default, nor custom, file properties. (Although you could probably write custom code that does that.)
Steve Clark, MCTS | Twin-Soft.com