Under the hood

Most of the purported 200 changes in Mavericks aren’t new apps or features — they’re cosmetic overhauls and performance improvements. Apple promises this is the most powerful and power-efficient operating system in its history, with everything from a 35 percent decrease in consumption while you watch video to a Power Saver mode that lets you choose when to run the browser-crippling Flash plugin instead of having it destroy your computer automatically.

Even this early, Mavericks is fast and stable

App Nap is a lot like the power-saving features in iOS 7, pulling power from background apps to save battery. Your apps can now even auto-update, which should at least make John McCain a very happy man.

There’s plenty more, and at such an early stage it’s hard to really evaluate the improvements anyway, but even with a few bugs and problems it’s already a fast, stable operating system. But there are some new toys to play with as well, both big and small. And it’s the small things that might be the most significant.

Notifications

If the only change in Mavericks were an improvement to OS X notifications, it’d still be worth the 4.79GB and the hour or so it takes to install. On one hand, you now get more notifications than ever — many of the same things you’d see on your phone now come to your computer as well. You can also now interact with your notifications, in an awesomely Android-like touch; click on a Messages notification to reply inline, or delete an email without ever needing to open the app. I can’t help but hope that Apple brings the same thing to iOS 7 sooner rather than later.

Mavericks is worth the upgrade for in-notification replies alone

Notifications are more accurate and more immediate, though it’s still not nearly as full-featured and customizable per app as Growl, and unfortunately you can’t prevent the notifications from taking over the top-right corner of the screen, which is the last place I want them to be. I particularly appreciated the addition of a more obvious Do Not Disturb mode, which makes it easier to shut out the world and get some work done without email notifications getting in the way every ten seconds.

Though Apple didn’t mention it in its keynote or the Mavericks release notes, Messages has also been improved. Which is to say, it’s not a huge mess anymore: the app is much faster, almost never beach-balls while it loads, and no longer seems to crash my computer every time I try to send a text message.

Displays

OS X has never been good with multiple displays, and things only got worse with Mountain Lion — if you have an app set to full-screen, the other monitor just becomes completely useless. With Mavericks it’s much smarter: you can run a full-screen app on each monitor, which is what it should have been all along. There’s also now a menu bar on each screen, you can move the dock wherever you want, and each screen’s Expose feature shows only the apps on its monitor. Even AirPlay is better, allowing your TV to be a wireless secondary display instead of just forcing you to mirror at awkward resolutions.

Using multiple displays works like it always should have

It’s all pretty seamless, and the setup feels like it should have been all along. If you use multiple monitors, you previously had to choose between using Apple’s cool features and actually taking advantage of your two monitors. Now it just works.