My problem with this movie lies in the gender stereotypes it perpetuates.
First, there are too few female characters. Second, the ones that are present are highly stereotypical.
The female squirrel uses her feminine wiles to manipulate the male. Ultimately, she is rescued by him and, of course, falls in love. Once the two are "married" she turns into a bossy shrew and he longs for escape. Terrible messages all around.
Then there is Ellie. I see that other people consider her a strong role model, and in many ways she is. She is brave and courageous. Yet she is held back from rescuing Sid the Sloth because she is having a baby. How convenient that the baby comes just as they are about to go on the most dangerous part of their mission, which keeps her out of the hero role - a situation that is all too common for female characters in kids' movies.
What kind of message does this movie send about women? They are either manipulative vamps or beatific mothers who are strong enough to bear children but not qualified to be rescuers.
On the male side, we have other stereotypes, namely the idea that men cannot talk about their feelings. Manny is very uncomfortable admitting how he feels about his friends. Ultimately he is shown to be wrong in this belief, but his discomfort never quite goes away.
Very unfortunate. This film was funny and had lots of action, but it sends entirely the wrong message about gender.