I saw Tangled the other day. It was your usual Disney girl (Rapunzel) meets boy (Flynn) movie with a couple of funny animals thrown in to make the children laugh. We enjoyed it. It was fun and full of action, but I won't bore you with the plot details. You can read plenty of reviews online. Here and here are some pretty thorough ones that discuss issues parents of young children may need to be aware of, like scary scenes and brief violence. I thought the issues raised in such reviews turned out to be fairly minor.
I did think there are some other issues worth being aware of (in order of significance).
1. Mother-Daughter relationship. This was by far the most significant issue for me. In this version of the story, the wicked old women who imprisons Rapunzel pretends to be her mother. Rapunzel believes this and is sure she is loved very much. In fact the real reason she is 'cared' for is much more sinister. She is not shackled by chains but by emotional manipulation. She is told that "mother knows best". Now, we know that the right thing for Rapnzel to do is to escape and return to her real parents. But she knows nothing of her real parents and such escape would be in blatant contradiction to her 'mother's' command. When Rapunzel is struck by remorse for her disobedience in leaving the tower, Flynn tells her that rebellion is part of growing up and she will just have to "break her [mother's] heart and crush her soul". A turning point in the story is when Rapunzel says, "no!" to her 'mother' and refuses to do what she is told. While all of this is consistent and necessary in the plot (set up the way it is), it is a confusing model of a this important relationship for young children.
2. Life-Purpose. "Princess" movies are all about finding the prince. While this movie differed in that she was finding her parents, the plot spent a lot of time developing their (Rapunzel and Flynn's) relationship: falling in love and eventually getting married. Now I have a high view of marriage and I like that my girls would like to get married. But at this young age I would like their purpose in life to revolve around something other than finding a husband. There are other things to do and more helpful dreams to dream.
3. Body-Shape. As you can see in this picture, the bloke has arms like tree trunks while hers are like matchsticks. This (admittedly typical) stereotyping infuriates me by the way it presents completely unrealistic body images and ridiculous relative sizes between the man and woman. Whether we like it or not, these images form our expectations of what our bodies ought to look like. They are not helpful.
If you take your daughter to see the movie, I recommend discussing the first issue. The others are ones you'll be fighting all the time; they're not particular to Tangled.