So far, I have only seen the first episode so I can only comment on it. From what I saw, they obviously took a great amount of artistic licence in the story of the main character. After all, it's not like someone was actually writing down everything that was said and done so the basic people likely existed but outside of that, they likely made most of it up to make the series more interesting.
As far as the historic events, I would say they are accurate. Slaves came from Africa and sold to people in the U.S. They were crowded below deck of ships. When they got hear, they were purchase by people. Some of their masters were okay and treated their slaves with some measure of dignity and kept families together, where others were far worse and treated them like cattle or property to be bought, worked, bread and have their offspring sold to other masters. These things are historically accurate as they did happen in many places. Maybe not to the specific people but to many slaves.
One thing that they made more accurate is how slaves were likely captured to begin with. I had to laugh at the older series when they showed how slaves where captured by white people. Think about it, a bunch of white guys who had never been in the African Jungle trying to capture the people that lived there. Sure, they had guns but your not going to shoot someone you plan to sell as a slave. Thing is, the Africans would have no need to capture people who are invading their land and they would have outnumber the white slavers by a large margin. Basically, if the jungle didn't get them, the people they are trying to catch would. If they managed to capture any, odds are they would not make it back out alive. If they went in with 10 people, they would be lucky to come back with any much less any slaves.
I believe the new miniseries Roots is historically accurate - even more so than the first. With 40 years of historical research since the original, new facts have been discovered and it is apparent in this series. The creators teamed up with historians to ensure the accuracy of the miniseries,
The miniseries Roots has historical inconsistencies. The book itself claims there are fictional embellishments. There are also inconsistencies between the story and historical documents. This includes the family lineage. Haley used the term "faction" to indicate a mix of fact and fiction. It is important to understand what is real and fiction, although the story stands the test of time.
The new miniseries Roots is not historically accurate because it attempts to dramatize historically true events to draw ratings. In all cases of the entertainment industry, follow the money. What makes for higher ratings and more money - the truth? Or, a dramatized representation of otherwise true events? Watch the series for purely entertainment value.
I don't think that the new miniseries Roots is historically accurate, based on the clips I have seen. I believe that it is rooted in history, and it is a good way to start learning about slaves and the Civil War. However, you cannot take a TV miniseries as fact.