Oh come on with the good reviews, even if she wasn't an evil slave trader, the film comes across as a melodramatic propaganda piece from start to finish...
... but then again, it was a melodramatic propaganda piece from start to finish...
... but that's not why it's one of the movies with a huge disparancy between critic and user reviews on the more reputable sights. It was intentionally polarizing. Rational people are ripping into it because they turned a power hungry monster responsible for the slave trade and a fair amount of ethnic cleansing into an anti-slavery hero. It was a monumental rewrite of history from start to finish, one so extreme you can't even give it the excuse of artistic license.
And it was intentional, there were a lot of other people that you could make a heroic movie about that fit the mold they were looking for to push meh message. But they chose this one because the point wasn't to praise the historical figure, the point was to praise the total rewrite of history.
And make no mistake, that is the reason for the positive reviews. They don't care that it's a cheap poorly written over-acted political propaganda flick, they are praising the fact that they blatantly and knowingly rewrote history, and then turned around and said "we don't care, it's rewritten now, we have changed reality and, guess what, all of our goose stepping followers don't care either."