The news was released today that Idina Menzel will be performing the Best Original Song nominee during the ceremony and not Demi Lovato. In addition to Menzel performing, we will also see "Happy" from Despicable Me 2 performed by Pharrell Williams during the ceremony. "Let It Go" is the clear frontrunner as it is part of the longest standing #1 soundtrack since 2003 and prompted Disney to re-release Frozen in sing-a-long formats.
I wasn't a huge fan of Frozen, but I will admit that "Let It Go" is a great song. I think it's right for them to choose Menzel to perform, as well. If you haven't heard "Let It Go" just yet I would give it a try.