Donald Sutherland plays Mountie Dan Candy as if the character he knew he was in a movie and kept pushing it to be an action/adventure film, or a revenge movie, or a revisionist Western with a hero who could make a difference - but he's not. He's in an historical docudrama about a series of related domestic tragedies. Which means that the outcome is predetermined, and after insisting he has some power to effect matters for the better, he is left with the Indians to witness the end unfold.
This is the clue to the real strength of the film, which many would find its greatest fault. It is indeed slow, in order to accommodate an elegiac visual style. Tone and effect - essentially of sorrow, and of powerlessness over the historic inevitability of it all - form the real substance of the movie.
It's understandable that such is not to the taste of many audiences. But the film makers do deserve credit for attempting to approach their material in this fashion, rather than opt for something more profitably "exciting." That said, it must be admitted that a large scale production like this is operating on what appears to be a crash budget, and that doesn't help. It certainly didn't help in the preservation of the film, the available print on DVD is pretty bad. But occasionally the cinematography rises to the majesty that the script and director are calling for it, and eerie and beautiful moments pop up in the film, often when you least expect it.
Not really a success, but by no means simply a failure.