Olaf's childlike innocence might not work for everybody, but for those who would like to give Olaf a warm hug, the song is great. In Summer: Whether you like or loath "In Summer" is going to depend entirely on how you feel about Olaf the Snowman as a character. Disney villains almost always get great songs to sing and if you pay attention to the lyrics, you realize that what Hans is really saying is that Anna's love is an opportunity that he can take advantage of. First, it's the love song, as the pair sing about how they're falling in love with each other.
Love Is An Open Door: Sung by Anna and her new beau Hans, "Love is Open Door" is one of the more interesting pieces of music in Frozen because it fulfills two roles that we normally see songs have in Disney movies. However, it also shows us what Elsa wants, which is for all this to just end, showing how the sisters will conflict later in the story. In Frozen, that song is "For the First Time in Forever." It's mostly sung by Anna as she revels in the excitement of seeing the castle gates opened for the first time in years. The song in which the protagonist sings about their dreams which will drive the plot of the story. For The First Time In Forever: Every great animated Disney movie, and most musicals in general, have what's called the "I Want" song.