I think it was a GREAT idea. The World Trade Center was what, two years old at the time? Most Americans still hated it because it was too "modern." I think it's interesting that another country (at least, according to this ad agency) already saw the WTC as a symbol of America, even when most Americans didn't.
Thinking about it sans terrorism, it reminds me of Jacques Tati's Playtime, where you only see the landmarks of Paris reflected in shop windows. This is the reverse of that- you see the landmark, and the tourists (people seeing the ad, in other words) are implied. That's what makes it a brilliant ad, to me.
i remember seeing that ad and appreciating it then.
i was thinking of surfing your site, dabs, for more use of spanking in ads. This one just kills me: Blow smoke in her face, you poseur! She'll love it!