The Humans by Matt Haig

When an extraterrestrial visitor arrives on Earth, his first impressions of the human species are less than positive. Taking the form of Professor Andrew Martin, a leading mathematician at Cambridge University, the visitor wants to complete his task and return home to his planet and a utopian society of immortality and infinite knowledge.

He is disgusted by the way humans look, what they eat, and the wars they witness on the news, and is totally baffled by concepts such as love and family. But as time goes on, he starts to realize there may be more to this weird species than he has been led to believe. He drinks wine, reads Emily Dickinson, listens to Talking Heads, and begins to bond with the family he lives with, in disguise. In picking up the pieces of the professor's shattered personal life, the narrator sees hope and redemption in the humans' imperfections and begins to question the very mission that brought him there--a mission that involves not only thwarting human progress...but murder.