Fanon wrote this in 1961 when the world was locked into the Cold War between the USSR and the USA, and postcolonialism was in its infancy. As a psychiatrist as well as a political philosopher and revolutionary thinker, he was especially interested in the psychopathology of colonialism, what it means to be objectified as a 'black', a 'native', somehow a 'sub-human'.
His chapter 'On Violence' has especially been misquoted and simplified, taken as an incitement to violent revolution, rather than as the intellectual analysis of the intrinsic violence of imperial colonialism and capitalism.
Like all texts and thinkers, this reflects the material, political and economic conditions of Fanon's time - but there are reasons why he has influenced and been quoted by people as diverse as Malcolm X, Steve Biko, Che Guevara... and Barack Obama.
Most of all, this book analyses the way in which colonialism sets up a fundamental opposition between the colonist and the colonised as two essentially separate species with all the chilling implications that entails.
Today's world isn't, of course, the same as it was in 1961 but that doesn't mean Fanon is no longer relevant (just as we still read Freud, Darwin, Descartes, Marx even though 'our' world is very different from the worlds which shaped these texts). It's worth reading Fanon especially against Edward Said (Orientalism
, Culture And Imperialism
) and Foucault.