The title of my review might be surprising, since this is supposed to be a book on topology. But Kelley says it best in his introduction: he intended to subtitle his book "What Every Young Analyst Should Know." As such, you will only find point set topology in this book--no algebraic or differential topology, and no mention of manifolds. I suppose the point of the book is to shed light on the topological structure of spaces of continuous functions on locally compact, Hausdorff spaces. This is really too restrictive to do the book justice, though. Kelley also discusses nets (vital in functional analysis, where non-metrisable topologies abound), characterisation of metrisability, uniform spaces, etc. Anyone interested in analysis, particularly functional analysis, should be familiar with these topics, since function spaces often have topologies which are not metrisable. In such spaces, sequences are often not enough to test for closure--nets must be used. Similarly, uniform and Cauchy properties must be reformulated in the guise of uniformities. Kelley leads the reader through all of these thickets in a clear style.
The only complaint that can be made against Kelley's book is the lack of examples in text. However, he makes up for this with numerous exercises that generally revolve around important examples of topics discussed in that chapter. Despite his lack of examples, the text is still quite clear. His proofs are very complete, and he is a true stickler for detail, something that is vital in such an abstract setting as general topology. To wrap up this review, if you are interested in "topology" as usually considered at universities, this probably is not the book for you--it is an excellent reference for point set topology, but the powerful machinery of algebraic and differential topology is not here.