What's the main improvement in the three-day-old Mac OS X 10.5.2? Increased stability. With previous versions of Leopard, I had to force-quit a frozen application once or twice a day, but with 10.5.2, I haven't had to do it even once. "It just works" is once again a description of the Mac, not just wishful thinking, as it has been since Leopard shipped in October.TidBITS provides a thoughtful review, saying the update "marks the real beginning of Leopard:"

With their release of 10.5.2, Apple has fixed a number of things that I, other reviewers, and legions of actual users have complained about, and developers and Terminal-level clever folk had come up with reasonable workarounds for that can now be mostly abandoned.

The other major upgrade in 10.5.2: Apple changed some menu bar behaviors that many users found annoying. Until now, the Dock and menu bar were translucent, which users who use photos as their desktop wallpaper found confusing. TidBITS explains: "The way I decorate my computer's desktop with my own photographs, the menu bar's transparency rendered it all but illegible, the text in the menu bar being drowned out by the photo colors showing through from behind."

The workaround was a hack that required delving into the Unix operating system that lies at the core of Mac OS X. Now, users can set the menu bar to be fully opaque using a checkbox in the Preferences panel of Mac OSX.

Unfortunately, the Dock is still translucent; if you want to change that, you still have to dive into Unix. TidBITS has instructions.

Apple also made popular changes to the behavior and appearance of folders in the Dock. They act and behave more like folders do elsewhere in Mac OS X, rather than acting and behaving like Stacks, which was a new feature of Leopard. You can still have Stacks, though, if you like Stacks.

I didn't have much of an opinion about the changes in Dock behavior between Tiger and Leopard. However, many people do hate it. A word of advice to Apple: Let go of the translucent dock, it's not buying you any love.

I am enjoying the improved stability of 10.5.2. And it's not just more stable -- the Mac also is faster and more responsive when 10.5.2 is combined with a graphics update that Apple released the same day.

Apple describes dozens of additional changes in the update, which weighed in at about 150 MB for me, 180 MB for the TiDBITS author. The size of the update varies based on your own configuration, but it's pretty big, equivalent to a service pack from Microsoft.

New features include improved reliability and stability of AirPort connectivity, and bug fixes and support for additional devices in Active Directory, Back to my Mac remote access, Dashboard Widgets, iCal, iChat, iSync, Finder, Mail, Networking, Parental Controls, and more.

World of Warcraft players are loving 10.5.2, reporting double frame rates. I've been able to double Second Life performance, too -- but Second Life is still a pig on Leopard; previously, it was running at 1-3 frames per second, now I've got it running at 4-6 FPS. Second Life has got a long way to go until its performance is good; Linden Lab recommends 15+ FPS.

Update Feb. 15: Subsequent to posting this blog, I got a Twitter message from a Second Life friend who says that the performance of the new version of the experimental Windlight client is much better than previous versions on the Mac. She was right: I was running 5-20 FPS in my brief test. Thanks!