Apple, welcome to Microsoft's world, a world of constantly sending out updates to counter new security threats to your desktop operating system. That's the big story behind the latest Mac OS X Lion update, 10.7.4, which patches 32 vulnerabilities. Though the update doesn’t bring new major features, it does fix some behaviors even beyond tightening security. Maybe the biggest addresses a problem where restarting always opened the apps that were running when you shut down, even if you hadn't chosen that option. Quite a few fixes apply to business use of the OS. And finally, a hardened version of Safari is included.

None of this effects our overall verdict on Mac OS X Lion: Each new version of Apple's desktop operating system resets the bar as the best consumer-level operating system ever created. At just $29.99, OS X Lion continues the tradition. It includes convenience and safety features never seen before on a desktop operating system, with the latest of these being iCloud syncing to iOS devices. Lion also can save documents automatically as you work—so you never have to save a file and can recover previous versions effortlessly and can start apps automatically in the same state they were in when you closed them. Lion also includes hundreds of major improvements and minor tweaks that combine to make OS X both the most convenient and the most powerful operating system ever.

The three main things you need to know about OS X Lion are these: It's faster and more flexible than ever. It's more powerful than ever. And you don't have to climb a learning curve to use it. Read on for the details.

Three things to know about Lion:
First, OS X Lion is easier to use and more flexible than ever. The interface now includes some ease-of-use features taken from the iOS operating system used in the iPhone and iPad. Also, at long last, OS X 10.7 Lion borrows from Windows the few interface features in which Windows still had an advantage, such as full-screen windows and resizing from any window border, not just the lower-right corner as in earlier OS X versions. Lion's feature that automatically saves and resumes your applications exactly where you left off is borrowed from iOS, and works only with applications that have been updated to support it.

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Apple's iLife and iWork suites get an immediate update that adds the automatic-save feature. Microsoft hasn't said when Office for the Mac will get updated to work with Lion's file saving feature, but I doubt you'll need to wait long. You probably won't have to wait very long for Adobe and other vendors to offer similar updates.

Second, OS X Lion is more powerful than ever. Thanks to its built-in apps, OS X 10.7 Lion lets you hit the ground running as soon as you start using it, unlike Windows 7, where you'll need to install third-party and download-only Microsoft software before you can view PDFs or run an e-mail client. Lion's Preview app, for example now displays and prints Microsoft Office and iWork documents in addition to PDFs and most graphic formats—something that Windows 7 can't do until you add Office and a PDF viewer such as Adobe Reader. A why-didn't-anyone-do-this-before feature called AirDrop lets you copy files to other nearby Macs without setting up networking—even if both machines are on different networks.

Speaking of networks, the 10.7.3 release added some networking capabilities that will be important in corporate settings. It also brings a new version of Server Admin Tools, fixes for Apple Remote Desktop. The update also improves features in the Server version of Lion, with better display of details about connected users, better VPN support (including a choice of enabling L2TP or L2TP and PPTP protocols), an improved Wiki server, and better Open Directory support.

A persistent headache for ex-Windows users is also finally eliminated: when you copy one folder over another with the same name, Lion finally lets you choose whether to merge or replace the existing folder instead of simply overwriting the existing folder and all its contents. Similarly, when you copy a new file over an existing file with the same name, Lion asks whether you want both versions or only the new one—and it does so with a far simpler dialog box than the nightmarishly confusing "Copy and Replace?" dialog in Windows 7 (though Windows 8 aims to fix this).