What is a brief summary with a critic appreciation of Edward Said's Orientalism?

In brief,
Said's  argued that the "Orient" was a mythic construct of
western European nations, a construct that served colonialist aims. The Europeans took all the
wildly varying cultures that ranged from Egypt to India to China and lumped them all under one
term: the "Orient." Said contended that there is no such thing as the
"Orient," except in the European imagination. To Said, calling all these cultures the
"Orient," as if they were a "monolith," served the agenda of Europeans who
wanted to exploit this territory. By taking vastly different cultures and labeling them all
equally the "Other," that is to say, inferior, feminine, irrational, less developed
and mysterious, they could all be seen as in equal need of firm, masculine, rationalist,
European control. 

A critical appreciation
would note that Said's book shook the foundations of Western thinking about the
"Orient." It has been enormously influential, even if it has been criticized (nothing
is perfect). The key point is that after Orientalism nobody doing serious
scholarship would ever look at those many countries and cultures spreading across half the globe
as an undifferentiated, "exotic," mass again. In fact, calling Eastern cultures
"Oriental" has now become politically incorrect. Said's work can be said to stand as
one of the most influential scholarly books of the last quarter of the twentieth
century.