I really wanted to like this movie. Modern day adaptations and twists on Austen can be wonderful, many on here have mentioned Clueless, another great one is the Lost in Austen miniseries.
The problem here is not so much the Mormon setting, but the limitations and constraints that Mormon culture appears to put on the writers in terms of plot. I gleaned enough of the cultural setting from other reviewers on here for that to more or less make sense (those reviewers are correct in that it's not very well explained/explained at all).
So what's good? It's nice, bright and colourful. Casting the five sisters as various college friends was an interesting idea. The main actress playing Elizabeth is very watchable. The actor playing Darcy is competent (even if he often looks uncannily like Adrian Lukas, who plays Wickham in the definitive BBC adaptation). Chemistry is more or less there. The quotes from Austen, had they been less hideously pinkly presented, were nearly an interesting touch.
The problem is tone. Austen's work is sharp and exacting, biting, witty and harsh. This was bland. It lacked edge. One got the sense that there was a culturally religious nicely-nicely thing going on here, and it just doesn't work with the background material.
There were slapstick moments that really jarred: particularly in "imagination" sequences - ie they didn't really happen. (Is slapstick perhaps a more tolerable form of humour to Mormons than satire or saucier wit?) Regardless, the movie should have had the guts to follow through with these moments if it wanted that tone, instead of: "no, not really! It didn't really happen, it was just in her mind!" every time. In doing so it weakened the heroine and made her look passive and victimy.
It's hard to fit a novel like Pride & Prejudice into a feature film length, as there are so many characters, and that weakness showed here. The writers would have been better to reduce the amount of female characters (Mary's and Charlotte's roles were mixed up anyway) and they did at least axe one of the Bingley sisters. But ultimately Kitty and Lydia felt very extraneous. From memory, Clueless was slimmed down in terms of supporting cast compared to Emma.
All in all it's a pleasant, visually colourful movie to watch. But it lacks edge, guts and is at times painfully naive. Which, given its religious subtext, is perhaps unsurprising.