I only read the intro, which is a plurality of the book, and quite dense philosophically.

What is the point of history? Is it simply a retelling of past events? As an object of critique, that would not be very useful. Hegel theorizes history to be the unfolding of freedom itself. We began society with slavery. The only way we could have freedom was if a few people enslaved many. Eventually, more and more people were emancipated. With the rise of bourgeois society (circa Hegel's era) the opportunity for everyone to become free has revealed itself. Now, in the current era, everyone can be free! That is, until capitalism, but that is for the Marxist's to elucidate. I would definitely recommend reading this to understand how Marxists see history.