I saw the movie and loved it! I didn't feel that it was sending the "opposite message of Beauty-and-the-Beast". True they did the make-over thing, but the previews don't show the whole story. In fact, she doesn't want to fit in with the "in girls" at her school and hides under a hat after the change. She sees that they are beautiful but shallow.
At a critical point of the movie, she looks very un-princess-like again, but makes the right choices. I don't want to give too much away (even though the plot is fairly predictable), but I don't think you would come away feeling like it was saying appearances are everything. Important maybe, but what is inside is what counts!
Check it out with an open mind and later if you don't like the message, talk it over with your kids.