It's certainly not great artwork (it's a crude hack job cranked out by a local printer when the shipment of real stamps didn't arrive on time). It's never been owned by anyone particularly famous (edit: well, the DuPont guy is somewhat (in)famous, but the stamp was extremely valuable even before he owned it). None of the people associated with its production are particularly famous. It doesn't play any kind of pivotal role in world history, or even the history of the former British Guiana.
The only reason it's worth $9.48 million is that there is only one of them.
