He was partly responsible for the 1952 revolution in Egypt against British colonialism which lead to Gamal Abdel Nasser assuming power and some of the planning and organization for the revolution took place inside Sayyid Qutb's home. Gamal at this time would pretend to be a good Muslim and exploited the support of Sayyid Qutb and his friends, and Hasan al-Banna's students, to take over Egypt.
Gamal turned out to be a perfect tool of US and British interests and it didn't take him long to start killing thousands of Muslim activists around Egypt. Qutb and his family had their own share of this. Qutb spent 10 years in prison, ended with Gamal hanging him in 1966 after a fake trial that had the entire world speaking out against it.
The West and Israel are scared of him and hate him with a visceral hatred because he was one of the most unrelenting critics of Western moral bankruptcy and their agendas in the Muslim world. As happens with everyone who has dared to speak out against the US and Israel, you won't find much positive information about him anywhere, especially not in English.
Many Muslims unfortunately believe the false information given against him and so you will find hatred for him among Muslims as well.
But as for those of us with functioning brains and hearts and who have actually read his books and his biography, we know that he was a good man, a man of rare intelligence and integrity, who lived his message, rejected all the wealth offered to him by Nasser and the US, suffered the worst tortures for years in his old age and died for the sake of Allah.
In important matters I suggest taking the opinion of more mainstream figures like Yusuf al-Qaradhawi, Ibn Taymiyyah, etc. But if you ever feel your faith is weakening, or you are losing hope, or you feel that Islam has too many enemies and too few friends, reading a page of his commentary is enough to rekindle the fire in your heart and renew your dedication to Allah.
I have only read him in Arabic, so can't speak about the power of his works when translated.
The correct opinion regarding Sayyid Qutb is expressed by Shaikh Yusuf al-Qaradhawi and Ibn Baaz, who say that his work contains vast amounts of good, but that he wasn't an infallible man and the seeker of knowledge should use many sources and shouldn't take Sayyid Qutb's works as scripture, the way some people use his works to justify violence by taking his words out of the context of his time and place in history.