In my view, Brown was a hero, despite the fact that his methods in attempting to bring an end to slavery were poorly construed and unsuccessful.

Brown intended to trigger an insurrection in order both to liberate the enslaved people and to destroy the existing government of the United States. He knew that under the conditions of the time in the 1850s, neither the individual state governments nor the federal government were going to bring about abolition through peaceful means.

In this, Brown was correct. However, the small body of men he enlisted for his operation to take over the Harper's Ferry arsenal could not possibly have held out against the authorities, and the enslaved people throughout Virginia and the other states correctly saw that a spontaneous insurrection had no chance of success and so refused to participate in it. Brown was doomed.

That said, he was a hero because of his idealism and his intent to try anything rather than to allow the status quo to continue without any resistance against it. In death, Brown became a martyr, and even many people who themselves were not especially in favor of immediate abolition began to admire Brown and to believe his cause was a just and heroic one, though his methods were impractical and wrong.

The Harper's Ferry incident actually galvanized both sides in the slavery debate and was one of the factors that brought matters to a head eventually, culminating in war a year and a half later. War was the only thing that could destroy the slavery system as it existed in the US, and this, of course, is what was accomplished finally and completely by the year 1865.

An excellent biography of John Brown is John Brown's War against Slavery by Robert E. McClone of the University of Hawaii at Manoa. I referenced a quote from the book in my earlier post. McClone does not see Brown as fanatical at first; but travelling to Kansas to protect his sons who had relocated there. He soon became radicalized in the slavery issue, and took matters into his own hands. Even if one can argue he acted in self defense at Potawatomie Creek, his preplanned attack on a Federal Arsenal with full intention to murder those defending the Arsenal and start a race war is villainous actions per se. Brown would never have been portrayed as a hero were the slavery issue not so polarizing.