Here are some words of appreciation (from several authors) for the man whom I consider the greatest living scholar of the Middle East in the English-speaking world.
I used some of his work on the Isma'ili Shi'is and the "Assassins" in my doctoral dissertation and, years later, employed another of his books as the principal text for a course on the history of the pre-modern Middle East. Now, I'm using some of his later books in a book manuscript of my own, to shed light on the background of contemporary trends in the world of Islam.
Astoundingly, Bernard Lewis has published valuable work in every decade since the 1930s — making distinct and even pivotal contributions to the study of early Islamic sectarianism, the history of modern Turkey, general Islamic history, the contemporary crisis in Islamic society, and so forth. I suspect, but cannot guarantee, that he may have slowed down a bit recently. (His latest book was published almost four years ago; that's an unusually long lull for him.)
It was only relatively recently, and with great satisfaction, that I discovered that this great Anglo-American scholar's political views were roughly aligned with mine.