Poor Harriet Beecher Stowe. She has been labelled a racist and condescending by some, but it would be hard to imagine a white American woman, being any less racist than her in 1851. She pretty clearly depicts whites as a group as worse than blacks. Uncle Tom's Cabin is first and foremost a piece of abolitionist propaganda. By that I don't mean that it is inaccurate. I think that it is a fairly accurate description of slavery showing it both at its worst and at its best. It is written as a polemical piece first and foremost and contains asides by the writer to the reader. A lot of people in the twentieth century decided polemical writing or authorial asides to the reader were bad writing. I don't myself think that at all. Dickens, who I think she must have read, does this all the time, and other great writers do this frequently. She is melodramatic, but I don't think that is necessary a problem either. The Bronte's and many other contemporary writers were also melodramatic. Finally, many people criticize her for Uncle Tom being a character that toadies to whites, seeing her as endorsing this. In fact "Uncle Tom" has come to mean a toadying black betrayer. That's also unfair. Uncle Tom is clearly inspired by both Job and Christ and is seen as a paragon of christian virtues, e.g. the ability to suffer and the ability to turn the other cheek. Stowe does not even endorse this as the only way. For instance, the character George runs away and actually shoots a white slaver who is pursuing him and he is definitely a heroic character.
Having said all this to defend the book, there is one criticism that to me is right on the money, and unfortunately that is that she is just not that great a writer. While there is nothing truly awful about her writing, there is nothing all that great either. Her Christian religion can stand in the way of characterization and subtlety. Her prose is fine. The whole book is overly long, in my opinion. It is not so much that she is bad, as that she is not great. She is a thoroughly competent writer.
As such, this book is most interesting as a piece of history rather than a piece of literature. Uncle Tom's Cabin was a book that in fact did influence politics almost as much as any fictional piece ever has. The Civil War would no doubt occurred anyway, but it was a rallying guy and a superb piece of propaganda. She certainly understood the many evils of slavery and does not really sugarcoat them. She shows how slavery degraded the slave owner. She shows how slavery could destroy the humanity of slaves or co-opt them into maintaining the institution and so on. A lot of times, people want to take a simple minded view of the evils of slavery, but this book does not. It is also very fierce and brave about what she actually tackles, and I was surprised at its explicitness for the period in which it was written. However, reading it could be a bit of a grind and I found that I had to force myself to go on from time to time.
So worth reading for historical reasons, but not for literary ones.