Well that didn't take long. Interesting facts about it's reception and success:
http://www.wired.com/underwire/2014/01/disney-frozen-broadway/
I can understand that it didn't ring bells for everyone, and there are those who will seek to explain their displeasure as objective rather than subjective, but the reality is that it is a great movie. There are some areas where it could improve, and perhaps we'll see that on Broadway, but as-is, it's fantastic.
I think the biggest problem nay-sayers have with it have to do with the fact that you could say there are co-protagonists. Anna is the film's protagonist, but Elsa overshadows her, and is given the better song and more interesting parts. While they could have made Anna's part stronger, or switched to make it Elsa's story, it wasn't a bad choice to make it this way. But it will feel weak and unsatisfying for people who want the story to be about Elsa and spend most of the movie watching Anna.
It's also not a very deep story emotionally. It has a lot of emotion, there's no doubt there, but the emotions aren't very complex. I'd argue they don't need to be, and that it's fine as it is. However no one really changed in the movie. Anna loves her sister enough to die for her - well Elsa probably would have done the same if the roles were reversed. The movie suggests Anna's eventual acceptance of the loss of her sister, but doesn't really drive home the fact that, in her mind at least, she had given up on having family, and was looking elsewhere for her happiness and relationships. But she doesn't change, not really, and she's the film's protagonist.
Elsa gives up trying to be what she's not. It's not that big a change, but it's the biggest change we have and is celebrated in the biggest song of the film. It's brought on by the stupidity of the parents, but of course Disney will never say, "It's the parent's fault" so, like so many other movies they kill off the parents so it's the fault of fate to have children not be adequately guarded. But the parents spent a lot of time between the trolls and their death keeping the girls apart, and forcing one of them to hide herself so completely that not even her sister would recognize her, and so forth. You can claim they're just short-sighted, or blame it on the troll's advice, but it's just not a strong setup. I feel like they could have gone in a different direction here if they wanted to toe the line on their usual "parents are good" rule. They didn't go far enough in blaming the parents to not follow that rule, but they didn't really break the rule either, since they took the parents away during a still-formative time for the girls.
Lastly, it would have been more interesting if Elsa actually became bad, or dare I say it - evil. Instead the movie merely conveys that she's running away, with bad consequences, but still cares for the people who arguably are the reason she's suffering in the first place. She only gets to "I'm free!" and never makes it to "Why should I have been made to suffer?" Perhaps she didn't have enough time to become bitter, but the fact that people were after her and attempting to kill her should have changed her mind. Wouldn't it have been more interesting is she had become a full-on villain, and her sister was able to save her (or make good on her emotional divorcement by banishing her) through what would have required significantly more effort and perseverance than the film did? But I suspect you couldn't give justice to this sort of story in such a short film.
All that said, these aren't criticisms of the film, merely different directions it could have taken that might have satisfied those who found the film less than what they were expecting. I believe the film to be fine as-is, and well worth the
positive reception.