Al-Hajj, who is originally from Sudan, was held as an "enemy combatant" without ever facing a trial or charges.
He has been on hunger strike since January 7, 2007.
Al-Hajj's wife, Asma Ismailov, spoke to Al Jazeera before she travelled to Sudan.
"Now I can think differently, now I can plan my life differently, everything will be fine, God willing," she said. Force fed
Zachary Katznelson, a lawyer from the Reprieve organisation has worked on al-Hajj's case since August 2005 and has visited him 10 times in Guantanamo Bay, the last time just three weeks ago.
"Al-Hajj is remarkably thin, he has been on hunger strike and forcibly fed through his nose while being strapped down, twice a day, for 16 months," he said.
"He looks like an ill man, he has problems with his kidneys, liver, blood in his urine and there are concerns that he may have cancer."
Katznelson said that the cameraman's release was probably motivated by political concerns.
"I think this is part of a larger picture between the United States and Sudan, that they are trying to bring those countries closer together," he said.
"Sudan, one of the primary demands they made to the United States, is if you want to normalise relations with us you have to give something back, and one of the things is the prisoners in Guantanamo Bay."'Telling the truth'
Martin Mubanga, a former Guantanamo detainee, told Al Jazeera that al-Hajj had refused to be broken by his experience in Guantanamo Bay.
"When I saw him in the last years [of my captivity] he became stronger as he took a stance against the American authorities," he said.
|"He looks like an ill man, he has problems with his kidneys, liver, blood in his urine and there are concerns that he may have cancer"|
Zachary Katznelson, Reprieve lawyer
"Basically he was a man of resolve, he refused to be broken because at the end of the day he was telling the truth, he was not a member of al-Qaeda."
Mubanga said that al-Hajj would not believe he was free until he was back on the ground with his son.
"Only then will it probably begin to sink in that he is free, on the plane he'll probably still be thinking he is in a dream, that it is not really happening."
Al Jazeera has been campaigning for al-Hajj's release since his capture more than six years ago. Al Jazeera concerns
Wadah Khanfar, Al Jazeera's director-general who is in Khartoum to welcome al-Hajj, criticised the US military for urging him to spy on the operations at the channel.
"We are concerned about the way the Americans dealt with Sami, and we are concerned about the way they could deal with others as well," he said.
"Sami will continue with Al Jazeera, he will continue as a professional person who has done great jobs during his work with Al Jazeera.
"We congratulate his family and all those who knew Sami and loved Sami and worked for this moment."