The 12” G4 Powerbook is regarded by many as being one of the best ever notebooks produced by Apple. Despite being replaced by the original plastic intel based MacBooks it still remained a highly sought after model long after it was discontinued. Many users preferred its aluminum casing to the cheaper looking plastic of the MacBook and because it had a smaller screen (12” vs the MacBook’s 13”) it was the ideal choice for users looking for an ultra portable Mac.
I owned the 1.33 GHz model and was very happy with its performance. It came installed with Mac OS X Panther, but thanks to 768 MB of RAM it also ran Mac OSX Tiger with ease.
The one aspect of the 12” PowerBook that I was a little disappointed by was the screen quality, it was a cheaper spec than the 15” & 17” models and as a result colours looked a little washed out. Thanks to a little app called SuperCal though I was able to improve the quality significantly, and if you're intending to use the PowerBook 12” with an external monitor you obviously won’t have any problems.
One definite plus point is the battery life of these Macs, in general use you should get around 3hrs from a battery in good condition. Although MAC OS X Tiger would be recommended for most of the PowerBook 12" range, higher spec models such as the 1.33 GHz with maximum RAM should also be able to run MAC OS X Leopard at acceptable speeds.