We look back at this incident in Kansas as historians and see now how important it was in terms of showing us who John Brown was, how committed he was to the cause and what he was capable of. People were dying every day in Bleeding Kansas in the 1850s, and while Brown's attack was ugly and brutal, it wasn't all that shocking for the time. What was noteworthy was how Brown so strongly advocated violent action on the part of abolitionists. He and his small band of men, along with some of his sons, defended Free State settlements and gained some national attention for doing so
In the hardline abolitionist community, Brown was admired by some, condemned by others, and remained controversial in the anti-slavery movement and nationwide up until his death. Pro-slavery activists and newspapers tended to argue that all abolitionists were like John Brown (which wasn't nearly true), and Brown along with others influenced some in the North to consider violence as an acceptable means to abolish slavery.
Most people, though, and nationwide, were horrified by his actions.