First off, I actually watched this movie. As many other commenters point out, it seems that a lot of negative "reviewers" are getting their talking points from the liberal media whose false narrative about Governor Palin this documentary largely discredits.
As to the quality of the movie, I'm not one for documentaries, so I don't really have a basis for comparison. I thought it was well-done and of professional quality. Some of the dramatic scenes (depicting nature's violence or smoke-filled back rooms) were clearly added for heightened effect, but they did not take away from the straightforward unfolding of the story.
The raw footage depicting Palin's speeches, crowds cheering, newscasters analyzing her sustained 88% approval ratings, and the like, are matters of historical fact. There is no disputing that these events took place. Commentary from her friends, colleagues, opponents, and political analysts puts her accomplishments in perspective.
I found the movie riveting, and even though I was already familiar with some aspects of her career, some of it surprised me and some I had forgotten. For instance, the polling showing that McCain/Palin had pulled ahead of Obama/Biden until the financial collapse had escaped me.
I think anyone would be well-served to watch this, regardless of political affiliation.