I loved it too. I really had no expectations either, since I sort of shipped myself off to Japan for a month with what seemed like zero planning, and was therefore thrust headfirst into whatever came my way (even though I of course did plan everything...)
I went for 2.5 days and saw a bunch of the more popular pavilions (e.g.,Toyota, Hitachi) and was given insider's advice on which pavilions to avoid (Mitsubishi, Toshiba). All in all I was very satisfied, even though the food was inordinately expensive. Fortunately, I was treated to some delicious Chinese food by a friend from Nagoya.
I wasn't paid to be there, though. Does anyone know people got hired for country pavilions? Were they hired in their home countries or are they foreigners living in Japan. I would have jumped at the chance to work at the USA pavilion if I'd known about the opportunity earlier. Of course, I'd probably go crazy having to hear about Ben Franklin and his kite for the zillionth time...