Hitchens does use some pretty crazy terminology, but I have found God Delusion to be pretty simple, to be honest. Perhaps it's the knowledge of various sciences, I don't know, but I never really had a need to look up anything. On the other hand, Hitch was more about philosophy/politics, and threw plenty of curve-balls. And than, of course, there is a problem of me not being a native English speaker, which becomes much more apparent when it comes to nonscientific subjects, as most of the world shares the same scientific jargon.