Complex FT searches are hard to understand for end-users. Also it has it's limitations (cannot use dynamic date, string can only be 'contains'/'does not contain' and no 'equals, ...)
With the new DGQF, you have a very powerful search engine, which could be useful for end users to filter their documents.
It would be nice to have a wizard to help users building queries like this.
On top of that (but presumably far more complex to do) : it would be fantastic if end-users were able to do a search over multiple db's and have that result in a view/folder.