Hitchens' most lasting contribution is likely to be his anti-theist ideas.   He does not claim atheism nor agnosticism: he doesn't say the Christian or Muslim or other eternal, personal God doesn't exist, but that he is very glad not to believe in Him.   Hitchens' experiences as a political journalist helped him realise that human psychology invented God, since He is always a totalitarian being.

Hitchens other contributions are of like ilk.   They are excellent, simple, straightforware psychological ideas.   What they have in common is a love of the freedoms of thought and speech, and a deep love of being honest.   He doesn't like frauds or liars.   He tends to be emotional in his reasoning, but he doesn't lie about that fact or try to hide it.

The only criticism I'd offer of Hitchens, knowing that he never claims to be a philosopher or discuss truth itself in any depth at all, is he tends to rely on personality and charisma to argue his points. When he denounces all religions, including those who do not have an explicit eternal, personal God, such as Buddhism, he is denouncing not the falsehood in the idea of God, or other examples of falsehood that arise from unthinking that arise from religious gatherings, but the limitations religion puts on freedom of thought, behaviour, and speech. So he will argue (absolutely) that there are no absolutes, and that there is (as a perfectly true argument) no such thing as perfection. Internal contradictions are not obvious to him, because he is not on a philosophical plane of thinking. He is just trying to get people to think for themselves. He makes his arguments based on moral objections, for instance, that it's immoral to repress or punish sexuality (which is to him a lie against nature): if he relies on crude arguments such as 'sex feels good', it's probably to force a blatant reality into the field of awareness of people in religiously-locked denial.   The same for his deliberate use of a 'bad-boy' personality, or of sneering: he is saying, 'This is what a mammal is like, this is egotism, this is what human nature is. Accept it, don't hide it, and don't say it is original sin. Improve on it if you like.'

Therefore, it is really quite petty to criticise Hitchens for his faults. He is really just trying to establish that it is immoral to lie. He is not the one we should be criticising here.