Text macro is very useful, especially for reuse-blocks. Text maco provides flexibilities. For below example, You don't have to modify underneath circuit of the block if you hope use another part number, just re-define the text macro and add it to the block.
Text macro is different with Viewdraw's properties propagation( a script, see http://communities.mentor.com/thread/8072). Text macro does't change anything. I really hope Viewdraw team adopt this concept.