I worked constantly and deeply with Leopard before slogging through Apple's overwhelming master list of Leopard enhancements to make sure that Apple kept its promises. It did. That tedious work done, I'd rather relate some direct experiences with the features that just appeared when I needed them while I was using Leopard. It is by no means a representative sample or a greatest hits remix. Leopard doesn't lend itself to that. I'll just tell you about some of the things that jumped into my hand when I stretched it out.

The Bottom Line Mac OS X 10.5 (Leopard) Apple, apple.com Excellent  10.0 criteria score weight Ease-of-use 10 20% Compatibility 10 20% Management 10 20% Features 10 15% Security 10 15% Value 10 10% Cost: $129 Platforms: Macs with an Intel, PowerPC G5, or PowerPC G4 (867MHz or faster) processor Bottom Line: Apple's latest Mac platform software, released simultaneously for Intel and PowerPC-based Macs, marks a turning point for the Mac. Leopard users and developers immediately reap the benefits of Leopard's greatly enhanced Mac frameworks. Almost nothing is buried for Apple or developers to uncover, while users gain from Apple's unsurpassed attention to usability and effortless integration from stem to stern. Leopard will change the way you work with computers, and entirely for the better. About our Reviews and Scoring Methodology

No matter how big our displays are, they're never big enough. OS X is so slim and fast that Mac users immediately take up the habit of leaving apps and documents open so that they can easily multitask. I multitask best on the two-headed (dual display) Mac Pro in my lab. But an hour into any work session with that machine, I've managed to fill two displays with deep layers of overlapping windows and begun wishing I had another display, and then another.

Now I have them. Spaces creates a set of virtual desktops, each the size of your entire display, that you can flip into the foreground with one keystroke or one click. You can drag an application from one Space to another by dragging a window into the thumbnail for the destination Space. Apple managed to make cut-and-paste and drag-and-drop operations as easy with Spaces as if they are with one desktop, and actually easier than a two-headed system.

I took an immediate shine to Spaces' ability to open a given application consistently in an assigned space. For example, whenever I launch Xcode, Apple's development tool suite, it launches in a Space of its own. You might create one Space for RSS and IM, another Space for browsers, another for video, and another for Office. It's so easy to create, rearrange, and remove Spaces that it becomes as familiar as using the New item in a File menu. You can also pin applications to the screen so that they are present in all Spaces.

Applications that use Apple's OS X frameworks, as all native Mac GUI apps do, inherit an integrated spell check/correction facility that works the same in all cases. Leopard has added a grammar checker that catches a surprising number of gaffes made even by expert wordsmiths such as myself. All apps with text fields are also wired into an Oxford American Dictionary, updated in Leopard so that it's the sweetest online reference book this side of a forklift; and it's also an offline reference book — always there even when your network is not. Leopard also lets you submit the same query to the Oxford Thesaurus, and you can query Wikipedia from inside the Dictionary. Apple reformats Wikipedia findings to make make them more print-like, and Leopard displays a narrowing list of matching words as you type each letter of the word you're after, even for Wikipedia.

Mail and iCal have evolved, as individuals and as a couple. The face of Leopard's Mail client is familiar to Tiger users, but those on Outlook Express and Thunderbird have some adjustments to make, for the better.