This commentary might contain spoilers for the movie.
(This was originally geared toward the user "theprovinces" to help clear up any questions others might have from his critique.)
First, John Groberg did not produce this movie. He did not contact any production agents about it himself. They came to him after reading his autobiography. The director/producer Mitch Davis is not Mormon (as he indicates on the commentary), and further the majority of the other cast and crew that worked on the film are not Mormon either. The Tongan people are not put off by this film, but rather are very much in support of it. It is an acurate depiction of their lifestyle in the 1950's (did you realize that when you wrote this?). As indicated in the commentary, the people living on the island that the film was shot on were very much in support of the film. They even had a Polynesian prayer ceremony where all the tribal leaders and ministers of other faiths gathered and prayed for the successes of the film production, all on their own without any compulsion from the film crew.
You referenced the scene where Elder Groberg walks after the soles of his feet were eaten by rats. The director said that that really occured and it was not him being God-like or having a "miracle" happen. It was an event that was entertaining to the people on the tiny island. They really didn't have a lot to do in their day-to-day routines and it was funny to watch a man from a distant country walk after something like that.
As far as the girl seducing Elder Groberg and her mother wanting him to father half-white babies goes, something like that is not hard to fathom. As explained in the film by the girl's mother, that could have gotten them higher status in the tribe. But because he refused, they were initially insulted and shamed. It wasn't until he explained to the mother what true love means to him that she finally understood where he was coming from. And your comment regarding her being the "most beautiful Tonga(n)" is very opinionated. Regardless of the degree of attractiveness, his reaction would have been the same. She may have not been that attractive in real life, but if you were the producer, wouldn't you have done the same thing. They were only trying to point out his strong morals. (If you want to see what she really looked like she is at the very begining of the movie in one of the pictures of the Tongans.)
You were also incorrect in your reference to the "dead child". He was not breathing because of the mango in his throat, and therefore by all outward appearances dead. Once the mango was out, the boy remained in a coma because of his fall from the tree. The father of the boy was also Mormon, and brought his son to Elder Groberg because of the trust he already had for him. The director later interviewed the boy, now a grown man living in California, and he said the accident happened on a Tuesday and he woke up late Thursday.
If you couldn't tell on your own, the point of this movie is not to see who he ends up with. That doesn't matter. What matters is the life changing experiences both he and the people he taught went through. Yes these people were primitive, but Elder Groberg learns that that doesn't make them inferior or him superior. What it does show is that strengths can be found in everyone. They learned from each other. In fact the director states that Elder Groberg learned far more than he taught.
These people were not in need of saving (at least temporally), but are in fact a thriving intelligent community of people who do not need the things of the world. It is not like they were a polytheistic society. Several other missionaries from other churches, like Methodist, were already there, preaching the word of the Lord and about Jesus Christ. So if you attack him for being Mormon, you should also attack the others there that were of other religions.
Elder Groberg was far from being perfect. He was portrayed as being arrogant, as seen in the opening scenes with Anne Hathaway, determined as shown in the scenes where he learned how to speak Tongan, and frightened as shown in the scene where he and his companion were confronted by the small mob. Anybody knows that these are not qualities of a perfect person.
In no way is this movie racist either, unless your idea of racism is speaking the truth. This island culture was basically that of a third world country where access to things of the world and contact with the world was seldom available. They didn't always want that contact anyway, as observed when the Austrailian yacht came looking to trade booze for women and the people were desperately begged their own children to not go with them.
I am sure missionaries from any religion can relate to many of the experinces Elder Groeberg went through. Just because it is a film about a Mormon Missionary doesn't mean it's not relatable to everyone. The movie is not even about the religion, but it is about the experience of living with a culture unlike your own and learning that everyone has a mission in this world. Elder Groberg's story is one of truth from a very upstanding man, taken straight from his autobiography and authenticated by the people who lived it. I should know, I've met him and I know the kind of man he is.