I have over 20k photos in my iPhoto library. The problems he describes here are real. For me, it's more of a problem of retrieval. I want to search on more attributes than just date, location, face, and a flat tag structure.

Examples: show me... - all of the photos of people from my uncle Harold's side of the family (cousins, etc.) - all of the photos containing the blue car I used to own. - all of the photos containing both person1 and person 2.

This would require a significant expansion both in the complexity of metadata as well as automated tagging. I wish Apple would make it happen.