What I liked about this book was how different it was from the movie. It had to be different of course. The book is told mostly as Nick and Norah's inner thoughts and how they feel their way through the date to end all first dates. These characters are more raw than we like on our movie screen and make lots of mistakes along the way. Also, because of the two dialogues, supporting characters are less important than the main characters which works for a book but may bore in a movie. However, the book is wonderful - vibrant, funny, and heart-wrenching. These are two people you are rooting for from the moment you read the first page.
I also love the character of New York City in this book. She is showcased in all her raw, gritty beauty that few can appreciate. I find I do prefer reading about it more than experiencing it in all honesty but I've seen this character in my fleeting visits to the City. Nick and Norah almost make me want to get to know her better at her core, away from the tourist areas I've usually frequented to find these corners they roam through or even to better appreciate the midtown areas that they themselves wonder why they are drawn to them. Old NYC comes off quite good in Cohn and Levithan's tale.
I also dare anyone to read this and not come away with a greater appreciation for music. Nick and Norah are both characters that feel music deeply and are able to express their feelings about music in clear, interesting ways. It is a book with a soundtrack always playing in the back of your mind. Norah calls them "music soulmates" at one point in the book, a line which made it into the film, and I think it fits. Nick and Norah use music to catalog their lives, to relate to the world around them, on a level I'd never seen before. It comes across more in the book than the film but even in the film, you understand that what initially brings these two people together is that somehow, in some way, they are both listening to the same song in their head, they just haven't realized it yet.
I would recommend both book and movie as two different stories with two different main characters who happen to share similar traits and problems. Both will not fail to entertain and at the very least, they come with their own killer soundtracks.