The plot and the message are actually good. It isn't about following your heart or disobeying your parents. It's about love, both filial and romantic. It also says straight out that marrying someone you've only known for one day is silly.
In my opinion, (since people are actually talking about this) the songs were not as spectacular as Tangled, or as finished.
Now, about the trolls, instead of being the traditional large, fearsome creatures of Nordic lore that turn to stone in the sunlight, they are little magical creatures that turn back and forth between stone and troll at will.
For parents wondering whether or not their children should see the film: there is very little crude humor, and it is very mild. They just mention nose picking, that young men give off rather pungent odors after working hard, and Olaf uses the word "butt" a few times, and he's a snow man, so his bottom is just a ball of snow. Some parents will take issue with the use if magic. It's a fairy tale! However, through Elsa's magical gift one sees that talents can be used for good or evil and one needs to be careful about hurting other people with your skills. The most important thing is to act in love.
All photos are from the downloads section of the Disney website: http://movies.disney.com/frozen/downloads/wallpapers
And, in case you've never heard of it before, ships really do crack up when frozen in ice. This was an added touch of realism.