The PowerBook G4 runs on the RISC-based PowerPC G4 processor, designed by the AIM (Apple/IBM/Motorola) development alliance and initially produced by Motorola.

[1] When Apple switched to Intel x86 processors in 2006, some design features of the PowerBook G4's form and aluminum chassis were retained for the MacBook Pro.

The two models featured a PowerPC G4 processor running at either 400 or 500 MHz, housed in a titanium-clad case that was 1 inch (25 mm) deep.

[3] The notebook was given the unofficial nickname "TiBook", after the titanium case and the PowerBook brand name;[2] it was sold alongside the cheaper iBook.

[citation needed] The new machine was a sharp departure from the black plastic, curvilinear PowerBook G3 models that preceded it.

In a review, Macworld's Andrew Gore praised the PowerBook's weight, wider screen, and Velocity Engine, but criticized the difficulty of replacing the hard drive.

[6] ATPM's Trevor Boehm rated it "excellent", describing it as pricy but a good desktop replacement, and praising its speed, screen, and ports, though he criticized the trackpad as oversensitive and inconvenient for drag and drop.

[7] PC World's Carla Thornton praised its design, screen and performance, but criticized its graphics, DVD speed, battery life and price.

At least one aftermarket manufacturer began producing sturdier replacement hinges[9] to address this problem, though actually performing the repair is difficult as the display bezel is glued together.

Notably, the 12" model brought a welcome return to the Apple subnotebook configuration, conspicuously lacking in their product line since the discontinuation of the PowerBook 2400 in 1998.

CNET's Molly Wood described the 17-inch PowerBook as a "rock star's notebook", praising its design, screen, bundled software suite (which included iLife, QuickBooks, OmniOutliner and OmniGraffle), and backlit keyboard, though she said that the keyboard backlighting required the room to be quite dark, and that there was no option to increase its sensitivity.

In benchmarks, she found that the 12-inch, 15-inch and 17-inch models all had about the same "acceptable" battery life, and that the PowerBooks had similar performance to the 17-inch iMac desktop.

[14] Some owners have experienced failure of the lower memory slot on some of the 15" models, with the typical repair being the replacement of the logic board.

Apple previously had a Repair Extension Program to fix the "white spot" issue on its 15" PowerBook displays.

[16] There has also been a rash of reports concerning sudden and pervasive sleeping of 1.5 and 1.67 GHz models known as Narcoleptic Aluminum PowerBook Syndrome.

Another cause is the trackpad area heat sensor; system logs report "Power Management received emergency overtemp signal.

[a][11] One major factor that led to the discontinuation of the PowerBook G4 was Apple's internal experimentation with the PowerPC G5 for the company's next line professional-grade notebooks at that time.