@harpazo,
That depends on your purpose.
If you are looking for serious study, I had luck with Schaum's outlines (I used them to prepare for an advanced calculus course after I had been out of college for 12 years). They are a little sparse and not designed for "comfort". But they have the right material and if you work through the problems you will master it (at least in my experience).
I have never looked at "Math for Dummies". I have looked at some of the other "for dummies" books on different topics. I didn't find that they covered the subject with any depth. If you are looking for a summary overview they should be fine, if you find them enjoyable.