Squirrel Girl is delightfully awkward and nerdy. She shares some of the same space of geekiness as Ms. Marvel, but with much less self-awareness. And while not being self-aware, she knows where the fourth wall is, and regularly converses with it, like Deadpool but less squishy. All around fun stuff. 
 Also this collection included the original appearance of Squirrel Girl with Iron Man way back in the day. This story is also delightfully goofy, and inclusion in this first SG set was perfect, as there's really nowhere else that story fits.