At first, I hated this textbook. New to Analysis, I couldn't make any sense of it. But, I was trying do accomplish too much on my own without the help of the instructor. This textbook is terrible for self-study. A poor course instructor (you know the kind - the ones who read the book to you) can make learning Analysis a singularly miserable experience. However, if you're lucky enough to have an instructor that's willing to supplement and clarify the material in class (i.e. get you over the hump), you'll find this textbook quite adequate and worthy of keeping for reference. To get the most out of it, however, you'll need to be prepared to work much harder than you have in your previous math courses.
I know that there are two camps of reviewers of analysis books. There are those who complain that a text is too terse and those who say it's too wordy. This book finds a nice balance. It can be very frustrating at times...but, such is analysis. (Note that the authors warn you of this in the first paragraph of the Preface.) Mastery of the first two chapters is essential for one to succeed in the rest of the book.
I have given this textbook three stars because it let's the reader down on some topics. A couple of the proofs (L'Hospital's Rule is an example) are a bit too sparse in explanation for the beginner who must fill in the missing steps as part of his study. Also, a few topics are more notationally cumbersome than necessary, requiring the reader to be very adept with indexed summations. The chapter on Riemann integration is understandable, but falls short of most other texts in this area. (In my class, we used a different text for the Riemann Integral.)
If this is the required textbook for your upcoming Analysis course, I recommend that you read every section VERY carefully many, many times. Physically work through the examples and given proofs with pencil and paper. Many times the example proofs provide a model for the student that he/she can apply to the problems. If you still find it tough, make a separate notebook in which to write the definitions, thereoms, and even examples. Try diagramming the definitions and theroems, separating the conditions from the conclusions that they imply (don't forget what "if and only if" means).
The authors have included some very helpful appendices that should be treated with the same careful study as the rest of the book. Analysis is not a subject where one can pick up on a proceedure and calculate an outcome as one might do in Algebra or regular Calculus. One must learn to know and apply the definitions and thereoms logically. Well-known problem solving strategies still work here, but the method in which a student may be accustomed is entirely different (see How to Solve It: A New Aspect of Mathematical Method (Princeton Science Library) or, for proofs How to Prove It: A Structured Approach). Above all, rise to the challenge and don't get discouraged. All but the most gifted will find this subject difficult. Find help if you need it.
I recommend reading the linked books above before entering into analysis. Another really good book in the subject that will immensely help you is Yet Another Introduction to Analysis.