I daresay like most people, I wasn't expecting much from this film. But also, like most people I was very pleasantly surprised. Those who label this film as nothing more than a high-concept rip-off of Freaky Friday are really missing the point.
The body swap genre has been around for years, centuries even, and it is used well here to show each of our protagonists how the other side live, you see, the difference the film focuses on, rather than the gender difference, is the class difference between the two of them. Woody is living for high school, as Nell rightly points out, this is as good as it gets for him. No matter what happens, he won't get a great job, or be able to get a nice house in the city. This doesn't bother him to start with, but as he tastes life on the other side of the fence, the frustrations of the class system in American life start to get to him.
As for Nell, true, she would of probably had a prosperous life, but at the expense of her personality, her mother represents the person she would of become, an uncaring bossy woman who looks down on everyone who isn't as privledged as she. When she sees this, she realises that she doesn't want to be that person.
Yes, they fall in love, but it's nice to see this handled properly, as the couple overcome their differences, they start to see the good points in each other rather than focusing on the negative, and it's quite easy to see why they do fall for each other, plus it's kinda sweet too.