Granted, its rather hard to make a convincing case for Hitler as anything but a butcher. Its not everyone who manages to kill as many people as he did. I find it analogous if not equal to the issue of American domestic/foreign policy.
Hitler did wonders in regards to domestic policy. Well, at least for the non-Jewish, non-Gypsy section of the population. But in regards to foreign policy,...not quite so good. If you benefit a small number of people (your citizens) and harm everyone else (the world), the latter outweighs the former.
You could have picked a better example than the Nazis. Sure, the basic arguement is intact, but good luck trying to find much sympathy for the Nazis, and rightly so.