If theoretically "overrated" here means undeserving of it's praise, I'm being asked if it's worthy of being called the greatest animated movie of all time.
No. It's not the best ever. I liked it a lot. The songs were nice, the twist worked well enough, but it's not the best Disney movie ever. I'd hesitate to put it in the top 5.
While I love the movie itself, my biggest problem with it is it being interpreted as a revolutionary feature in female themes. "OMG, The first Disney movie where the girl is strong and saves the kingdom!" says teenage girls on twitter. I'm guessing none of them have seen Mulan. "I love how well they show the sister relationship. Disney has never done something like that before" say the same girls. They should try watching Lilo and Stitch.
It's a fantastic feature that's well made but not nearly as original as people act like it is. Disney has gone the female empowerment angle before, they've gone the family bond between siblings angle before, and while it might have been done better in Frozen than the other two movies, it's not the first to try.