A number of these essays fall into the category of literary criticism (lit. crit.) This is fine, as long as you have some familiarity with books or authors that are being "critiqued". If not, your appreciation might be less than full, although your curiosity might be piqued and you might be led to explore further. Zadie Smith's lit. crit. essays have a wide range so if,like me, you don't earn your bread from literary criticism some of the essays could be in unknown territory. However, you can pick ones on authors you know (e.g. for me, Forster, George Eliot, Kafka), and you will find Smith always offers perspicacity and instruction.
There are quite a few essays that are not in this category, or at least are only tangentially related to lit. crit. There is one brilliant essay, "Speaking in Tongues" (no. 9), which alone would justify buying the book. This essay starts from Shaw's Pygmalion, continues by way of Barack Obama, and shows the merits of being able to speak in many voices, to see things from multiple points of view. She points out that this is an ability which we cherish in artists but condemn in politicians. She holds up Shakespeare as a prime example of this quality, an author who is able to see from both sides: from black and white, male and female, king and commoner and so on.
The essays (nos. 15-18) on Zadie Smith's family are simultaneously touching and amusing. Smith's father comes across very warmly. Her account of her brother's career change into stand-up comedian shows great insight into this art. Smith's film reviews and the account of her visit to the Oscar weekend are also very entertaining.
All in all this is an excellent read, but be prepared to have your grey cells worked, and don't be afraid to pick and choose according to your tastes and reading background.