At its core, "Things Fall Apart" is a simplistic, no-frills, predictable tale. It's written competently enough, but there is absolutely nothing special or impressive about it.
Okonkwo is the proud, merciless tyrant of his African village, owning multiple wives and children, lording his authority over those weaker than him. Things fall apart for him when white colonists enact a less oppressive, fairer society that doesn't include Okonkwo holding absolute power.
I wish there was more to write, but the book is astonishingly bare-bones. Okonkwo is the only important character, and most of the story is concerned with mundane elements of his happy reign, such as the harvesting of yams or celebration of festivals. Even more problematically, Okonkwo is a rather simple fellow, relishing his strength and power, and despising those weaker him. It's probably an accurate description of a local African warlord, but as the dominant subject of "Things Fall Apart", there just isn't enough depth or intellect to him.
What I find curious is that Okonkwo, essentially a sadistic slave-owner using and abusing the serfs of his village, is portrayed as a tragic hero, while the white Christian missionaries, who teach that "all men are created equal" and that such abuse shouldn't be tolerated are the antagonists.
It's even more curious when you realize that Chinua Achebe has made an academic career from decrying perceived racism, and yet, here he is making a violent, selfish slaveowner the hero, and those fighting for equality the villains. Guess the fact that the former is black and the latter white changes everything though, doesn't it?