a friend of mine is a big fan of Nietzsche. the way I understand Nietzsche's philosophy, based solely on what he told me, is that you can't rely on written doctrines to design your code of ethics because relying on others to have one is what results in slave morality and self-subjugation. so the goal is to create values by contrasting them with the will to power (which includes self-control and the ability to attain personal desires).
I think this is a train of thought that gets taken for granted in the 21st century, so it's too easy to say he wrote "nothing insightful". you could argue that a lot of what the great philosophers wrote are "nothing insightful" to the average secular human of the 21st century, so of course it seems superfluous.
Additionally I think the reason his followers are "so radically different" is because there is both a left wing and right wing interpretation, where the left wing one is that the master-slave dynamic has to be eradicated from society entirely by subverting the master-slave binary (GWF Hegel, Jacques Derrida), and the right wing one is that a certain caste of individuals in society are entitled to primitive domination because they they reject slave morality (Ayn Rand, Adolf Hitler). I think Trotsky's points about Nietzsche are inevitably going to happen with any philosopher or philosophy.
But most importantly I think it's important to reject the idea that the left wing interpretation supports the ideas of utopian anarchist horizontalism, as I've seen with a lot of Anarchist postmodernists. Hegel's theory of history and sublation does not support the idea of "undoing hierarchies" in the traditional anarchist sense, but rather that hierarchies themselves reconfigure in such a way to make room for new hierarchies which counteract exploitation, abuse and struggle. It seems a lot of strains of postmodern Derridians and Foucauldians don't understand this and choose to preach the pseudo-dialectic towards radical horizontalism.