Al-Jazeera's impact and popularity pressured several state-run television stations to update output to compete. Several Arab governments were forced to lift, if only partially, media controls.
Analysts believe al-Jazeera is responsible for politically educating ordinary Arabs and for raising awareness and political knowledge of both Arab and world affairs. It is also credited with raising the expectations of the masses from their governments.
However, its reporting has made it unpopular with Arab and Western governments.
Al-Jazeera was banned from reporting in Iraq in August 2004, and its bureau has not been allowed to reopen since.
The station's programmes have led to several Arab countries recalling their diplomats and its bureaus being shut down or attacked in Arab countries.
I recommend Marc Lynch's Voices of the New Arab Public for anyone interested in better understanding the revolution in Arab politics which Al Jazeera represents.