Well, Napoleon certainly did leave fields of tens of thousands of dead and wounded after virtually every major battle he fought throughout the length and breadth of Europe. How many were the total dead and wounded at the Battle of Borodino? Wikipedia says approximately 70,000. In the twenty-first century we find numbers like this unimaginable. But even in the American Civil War a single battle like Gettysburg cost the Union some 23,000 soldiers (and that's not even taking into account the Confederate dead and wounded). Wars in the modern Western world have been fought on an entirely different scale than in previous centuries, up until quite recently.
Nevertheless Napoleon left behind him, in virtually if not all (I think actually all) countries he conquered civil rights for everybody (even or especially minorities like the Jews), in many places a modern legal code, and in many other places (such as Slovenia) a newly established national language (which is why today there is a statue of Napoleon in a major square of the Slovenian capital city - because he was the ruler who instituted Slovenian as the national language of the Slovenian government and bureaucracy). Napoleon was the actual liberator and bearer of the ideals of the French Revolution (liberté, égalité, fraternité) throughout much of Europe in the late 18th and early 19th century.
Napoleon's legacy is the complete opposite of that of Hitler and nazism, which sought to exterminate its so-called racial enemies in the interest of racial purity and "lebensraum." Where he could, Napoleon left in his wake civil rights, as well as constructive governmental and legal policies and procedures, whereas Hitler left behind only misery, deprivation, and destruction. Napoleon sought to build up Europe -- both western and eastern -- whereas Hitler sought only to tear Europe down.
