Is ISIS worse than the Nazis?

Well, yes.  Mark Steyn makes the point and drives it home in The Glamor of Evil:

Hitler felt obliged to be somewhat coy about just how final the final solution was. As Eichmann testified at his trial, when typing up the minutes of the Wannsee conference, "How shall I put it? Certain over-plain talk and jargon expressions had to be rendered into office language by me." Even the Nazis were reluctant to spell it out.

The Germans didn't have social media, but they had newsreels, and Hitler knew enough not to make genocide available to Pathé or "The March of Time". He had considerations both domestic and foreign. Pre-Wannsee, in Poland and elsewhere, German troops had been ordered to shoot Jewish prisoners in cold blood, and their commanders reported back to Berlin that too many soldiers had found it sickening and demoralizing. So the purpose of "the final solution" was to make mass murder painless, at least for the perpetrators - more bureaucratic, removed, bloodless.

As for foreign considerations, Germany expected to be treated as a civilized power by its enemies, and that would not have been possible had they been boasting about genocide.

Seventy years on, the Islamic State has slipped free of even these minimal constraints. They advertize their barbarism to the world, because what's the downside? Let's say the guys who burned Flt Lt al-Kasasbeh are one day captured by Americans. They can look forward to a decade or two of a soft, pampering sojourn in the US justice system, represented by an A-list dream-team that'll string things along until the administration figures it'll cut its losses and ship them to Qatar in exchange for some worthless deserter.

As for the upside, "the banality of evil" may have its appeal for lower-middle-class Teuton bureaucrats, but the glamor of evil is a far more potent and universal brand. The Islamic State has come up with the ultimate social-media campaign: evil goes viral! At some level German conscripts needed to believe they were honorable soldiers in an honorable cause, no different from the British or Americans. But ISIS volunteers are signing up explicitly for the war crimes. The Islamic State burned Flt Lt al-Kasasbeh alive not only to kill him but to inspire the thousands of ISIS fanbois around the globe, like Moussa Coulibaly, the guy who stabbed three French policemen outside a Jewish school in Nice this week.

Hitler spoke of a "final solution,"  a euphemism which could have meant the expulsion of the Jews from Europe rather than their murders. The Muslims of ISIS, Hezbolla - and other armed groups now conquering the Middle East and Africa are much more explicit: "Death to the Jews" they blare and death to the Great Satan (that's America for those who got their news from Brian Williams)