Actually, I have already re-read Anathem. The invented language does initially represent a barrier to understanding, but on deeper reflection, is key to what Stephenson is doing with this book. That is, examining the philosophical roots of our society as well as the antipathy to science so common in the USA today.
arth1 has me interested enough in the Litany that I will look for it. But I did find Anathem totally engaging and thought provoking, while providing an exciting ride from time to time. Very much like his earlier books, in that there are long passages with dialog where characters explain the zeitgeiss of the time, interspersed with occasional action sequences.