I have to second the opinion about the Missing Manual series by David Pogue. He is a long time Mac user and excellent writer, and is not afraid to call it as he see it (which means he covers the good, the bad and the ugly of Mac using).
The books are regularly updated, included access to the publishers website for updates, and links for software and shareware discussed, etc.
The Visual Guide to series is also good for total beginners. Its less in depth, but offers full color pics of every step along the way.