Many changes have been made in this second edition of A First Course in Real Analysis. The most noticeable is the addition of many problems and the inclusion of answers to most of the odd-numbered exercises. The book's readability has also been improved by the further clarification of many of the proofs, additional explanatory remarks, and clearer notation.
This book was a true revelation. After twelve brutal years of public school mathematics, having a book which moves from naive set theory to the integral calculus in only 200 pages -- and with strict rigor -- was a revelation.
(I read the 1994 version which isn't available anywhere anymore)