The new feature of tagging in document is quite useful, and I think it'll make people want to upload original documents.
One thing that seems a bit different from tagging in photos is that a name could appear more than once in a document. It would be great if tagging in documents allowed that. In addition, it'd be greater if we hover over one of appearances of a particular name, all the other appearances get lit up simultaneously. This solves another problem where a name appears at the end of a line and continues in the next line.
Not sure how useful this will be for other folks.