Infoworld gives OS 10.5 a glowing review. No one is unhappy with Mac OS X Version 10.4, known as Tiger. OS X is not an application platform (I bristle at using the term “operating system” for OS X; I explain why below) that needed repair, speeding up, or exterior renovation. Motivations for major upgrades of competing system software — roll-ups of an unmanageable number of fixes, because the calendar says it’s time, or because users are perceived to have version fatigue — don’t apply to OS X. Apple wields no whip to force upgrades because Tiger stands no risk of being neglected by Apple or third-party developers as long as Leopard lives. Despite the absence of a stick that drives users into upgrades of competing OSes, or perhaps because of it, Apple enjoys an extraordinary rate of voluntary OS X upgrades among desktop and notebook users. Why? People buy Macs because the platform as a whole is perfect, full stop. Leopard is a rung above perfection. It’s taken as rote that the Mac blows away PC users’ expectations. Leopard blows away Mac users’ expectations, and that’s saying a great deal.