I listened to her talk at Google on YouTube, which had a journalistic tone and was quite interesting. The part where she manages to show the kids Harry Potter over the objections of the censors and the evangelicals who want to show Narnia is amusing. If you look at the reviews of the book on GoodReads though, you get the idea that she spends a lot of it writing about how much she misses her boyfriend in NYC and other aspects of her personal experience not related to the subject. If it was to be a treated as journalism, those aspects would likely have been edited out, and probably not added in the first place. So, she did write something that was partially a memoir. Journalism is a bit more of a purist category, so memoir seems like the right choice for this book as it stands, however, it might have been better received if it were written as purely journalism.