My friends and I saw Frozen last Wednesday AND IT WAS AWESOME! I'm not saying it's one of the best, but it does show that the new Disney movies can hold a light to the classics.
The art and animation was gorgeous, the characters were very well-developed, and the story, while sticking with the traditional fairy tale plot, manages to break free from conventional Disney storytelling, especially with the third act which gives the biggest plot twist that M. Night Shama-lama-ding-dong wish he could still pull off!
However, its biggest weak point would be the music. Most of the songs were rather bland and formulaic and don't have the same "get stuck in your head forever and ever" factor that most classic Disney music has. (Seriously, one of the songs have the words "salad plates" in it!)
There are two exceptions. First is the very first song in the movie (which really does feel like an actual Disney song). And second is what is obviously the biggest and best song in the movie "Let It Go!" If you take the overall message of "Hakuna Matata!" and convey it with the same gravitas as "Part Of Your World", you get this song.
Words cannot describe how great this song is. You have to listen to it to experience it for yourself: