Nagel is well known for the clarity of his thought and writing. This small book is an excellent read for someone with little knowledge of philosophy. The topics are broad and interesting yet, by the end, you will be much closer to knowing whether you find philosophy interesting as a subject.
This book is well suited to its target audience: people with little experience of philosophy who would like to explore some very interesting ideas - and to see if philosophy is suited to them.
If you have already studied philosophy you will almost certainly find this a little too basic. If so, pick another of Nagel's books (he is a truly great and interesting thinker).