I just watched the first two episodes last night and I must admit I was a bit bored. Two many characters coming in and out made it difficult to care too much about them. Also, it seems historically innaccurate. Once the sioux got the horse, i don't believe they ran buffalo over cliffs anymore. It was easier and more efficient to hunt them from horseback. Also, the idea of the Lakota waiting to obtain firearms is ridiculas. A warrior society would grab on to better weapons whenever they presented themselves.
Over all I think it is terribly politcally correct, it is not historical. One more thing, how does Jed Smith cross the Sierra Nevadas and end up with the Mojave indians. Look at a map to see how riduculous that is. I could go on but I think you all understand