I've worked on this material quite a bit, and I think it's fair to say that Amalia is neither extra difficult nor extra easy. But you need an actual soprano in this role, and if you were to cast a mezzo -- say, someone like Emily Skinner or Annaleigh Ashford, who clearly have those notes but whose register sits naturally lower -- it would be a pretty tough sing.
As others noted below, "Where's My Shoe" is certainly a harder song to sing than "Vanilla Ice Cream," high B be damned. Those intervals are just super tricky, not to mention the fact that Amalia usually is moving all over the place while singing.
But Jerry Bock writes so beautifully for sopranos, and a song like "Will He Like Me" is the kind of song that's just a joy for so many sopranos to sing. If you've got a warm tone up high, it showcases the voice just effortlessly. And what a graceful, light ending!