Earlier quoted context omitted.
I think it's a compelling critique of Arendt that she basically just bought this characterisation wholesale - the Nazis had every reason to present their actions as 'banal' both in limiting the damages selfishly at an individual level and also limiting the damage to their ideology ('anyone could do it'). Eichmann was probably not the nazi-punchcard, mindlessly executing horrible plans, that she states.
The counter to that theory is the sheer amount of Nazi members in Germany - or really rank & file members in any fascist-like regime. That amount of people don't just go insanely evil on a whim, in most cases they are simply dragged there by mechanisms like Arendt describes.
I'd have to read her responses to the criticism she got again, I believe she did walk back the extent of her claims, but could be wrong (and in saying this, I'm sure someone will correct me if I am misremembering ;))