I have read Naive Set Theory, and may even have a copy somewhere. It is a good introduction to set theory for an advanced math major or a graduate student in math. It is only naive when compared to the treatment that a logician would give - it is basically "what mathematicians need to know about set theory in a nutshell". If you have a burning desire to understand how you get from the Axiom of Choice to Zorn's lemma to the Well-Ordering Principle and then back to the Axiom of Choice (thereby proving that all 3 are equivalent claims), this is your book. Otherwise I wouldn't recommend it.
If you're just interested in getting a sense of what higher mathematics is like, I would highly recommend something like The Mathematical Experience instead.