Don't believe the low ratings and reviews. This movie touches subjects like colonialism, imperialism and Islam. So of course many people will rage about the movie not being in line with their views or beliefs on the subjects. It's not a movie for peoples that need a "safe space".
I don't have any biases on the subjects and to me it seemed pretty fair. The movie doesn't depict the British Empire as all evil or all good. It doesn't depict the Muslims as good or evil either. It doesn't show the indigenous people in a particular good or bad light either. So I'd say the movie didn't sink into modern politics which is always surprising and refreshing.
As for the movie in general. Actors are great, scenery is great, music is good enough, costumes look good at least for someone not knowing exactly what costumes of the times are supposed to look like.
As for historical accuracy. According to Wikipedia, there doesn't seem to be a lot to go about with this story. The place was quite isolated in a time when info didn't circulate very well. So in this condition making the movie forces the artists to make romanticized relationships, characters and dialogs.
My main complain about this movie would be about the fact the guy's reign lasted around 27 years and this movie is more about how it all began. I felt it would have made a great TV show or mini series. So it's a bit sad that it felt like watching the first episodes of an unfinished show.
Also they tried to be a bit pretentious about the main characters thoughts. Thoughts they probably had no way to know anything about. So I wouldn't have made the choice to go with made up thoughts no one can relate to or care about. Yet it did provide some context of the time period.
To sum it up. This movie is quite ok, pleasant to watch and certainly no where near as bad as people are saying in the reviews.