You should try to see both sides of things, that is, both praises and criticisms, and consider the backgroud of these comments. As a first-course self-study material of mathematical analysis, I hold a negative point of view towards Rudin's series, since it is intended for those who have had solid knowledge of mathematical analysis and want to elevate himself to a higher level. Do not try to use it to establish some of your first important concepts in mathematics. If you have read Munkres' "Topology" before, you may understand what I mean by comparing it with Chapter 2 of baby Rudin. Another illustration is in page 21. After a long proof w.r.t. completeness, a word "isomorphic" will get you lost: we are working with a rather complicated mathematical object, that is, the Dedekind cut, how can we identify it with real numbers, that is, points of the real axis? Of course, the author here assume that you have already possessed some knowledge of abstract algebra. Have you? As the third example, the constraints imposed in definitions are often violated. This occurs frequently in the book when dealing with derivatives, especially in Chapter 10. Hard book does not mean it contains more things. This can be verified by taking a look at Apostol's "mathematical analysis".
For self-studier, choosing a right book is more important than choosing a "good" book. Study of mathematics is a long-term project in your academic career, so don't expect reading a difficult book once and for ever and then grasping everything. Reading Rudin's series before one is well prepared, according to my experience, will most probably mean a waste of time and effort without any repay. So, please think twice before plunging into Rudin.
Before study of analysis, one should have some prerequists, except for calculus:
1)mathematical logic and axiomatic set theory
For the latter, I recommend Karel Hrbacek, Thomas Jech "Introduction to Set Theory". For the former, I'm sorry I haven't found any suitable book for self-study.
2)abstract algebra and advanced linear algebra
3)general topology
As I mentioned before, Munkres' "Topology" is the only choice.
When self-studying analysis, the following books may be suitable and helpful:
1)Mathematical analysis: Apostol's "mathematical analysis"
2)Real analysis: Gerald B. Folland "Real Analysis: Modern Techniques and Their Applications". It is highly recommended to read Paul R. Halmo's "Measure Theory" beforehand.
3)Complex analysis: Lars V. Ahlfors "Complex Analysis".
4) Functional Analysis: John B. Conway "A Course in Functional Analysis".
Any comments are welcomed.