I think it was good. Not perfect, but it touched on some history that's always been hidden. In particular, the Scalawags, the Southerners of Northern sympathy.
The idea that great majorities in the North supported one idea and great majorities in the south supported another is wrong. The south was more committed because slavery was their economic system and they didn't see an alternative, plus the fear of a race war in the Nat Turner vein. But both sides had very substantial minorities who opposed the war.
We don't really know how strong this was, because only a few states in the South voted on the issue (Texas, I think was the only one that held a popular referrendum) and while the vote is pretty strong in favor, I seriously doubt that the KKK style voter intimidation was invented AFTER the war.
As a Republican, I was happy to see the struggles of the early Republican Party in the South shown. It was not easy fighting against the powers of the old South and they were brave and courageous. There were a lot of Southerners who were Republican in sympathy, but who were intimidated or frankly because of racism could not join a "black party." In fact, as the GOP began sinking after Reconstruction, many whites began a "lilly white" move to clean the party of its black base and try to repackage it for white southerners. This failed, ultimately because of anti-Northern hate, but also because the principles of the party outside of slavery were pro commercial and industrial and the South was predominately agricultural.