SPECTRAL7  The worlds most advanced operating system, patched very quickly ;-)  
(Version 10.6.1)

CARTER BECKETT  This update gave my computer all kinds of BUGS, including a bug that Apple had never

had to deal with before. Tech Support agreed with me that the beast thing to do was to

use timemachine to return the sustem to its preupdate state, and then apply the combo update (Doing repairs at every stage of the fix). This seemed to fix everything except that my Logitech Wireless laser mouse goes crazy every day, and I have to use the power button

to shut down my computer and reboot it.  
(Version 10.5.6)

MARK C  The 10.4.9 Server update has seemed to kill our email services.

it appears that it has damaged the Pearl core in some way.

We are not able to send or receive ANY mail.

WAIT FOR NEWER UPDATE!!!  
(Version 10.4.9)

MACUPDATE ADMIN  From MacInTouch.com:

"The folks at Unsanity may finally have unravelled the mystery of randomly-disastrous Apple software updates:

Shock and Awe: How Installing Apple's Updates can Render Your Mac Unbootable and How You Can Prevent it

... When you see the "Optimizing System Performance" phase of a software update, Mac OS X is really updating prebinding. Updating prebinding has a very, very nasty bug in it (look at _dyld_update_prebinding). If multiple processes are updating prebinding at the same time, then it is possible for a system file to be completely zero'd out. Basically, all data in the file is deleted and it is replaced with nothing. This bug is usually triggered when updating Mac OS X and every update to Mac OS X has the potential to render your system unbootable depending on if the "right" file is deleted or not. It's triggered during the "Optimizing System Performance" phase of installing an update. This phase is actually just running update_prebinding. If you launch an application that links to libraries that are not yet prebound, there is a chance one of those files will be zero'd out as dyld automatically redoes the prebinding on that file.

I've been tracking this particular bug for about 18 months now. Most of the real "random" failures reported on various Mac OS X "troubleshooting" sites after a user has installed an Apple software update are actually manifestations of this bug. By real I mean not imagined problems or ones that have been there for a very long time but the user is just now noticing it and artificially connecting the cause to the recent update (it's called Pareidolia). Yes, this nasty prebinding bug has been reported to Apple and yes, it is 100% reproducible if you want to reproduce it.

Every single time you install an update to Mac OS X whether it be an iTunes update, a QuickTime update, an update for daylight saving time, a security update, an Airport update, or an actual Mac OS X update, you can be hit by this bug. In order to prevent yourself from being smacked in the face by this bug, follow this simple rule: When "Optimize System Performance" appears during the update process do not touch your computer and definitely do not launch any applications. Just back away from your computer box as if it were a swarm of bees. Yes, it does mean that if you install the Mac OS X 10.4.9 update, you may get hit by the bug."  
(Version 10.4.9)

NICK  After installing the update, my cheapo printer stopped working, my wife left me, and I had *two* heart attacks.

Seriously though, I've had no problems at all with the update. I didn't even bother with the superstitious "repair file permissions before and after" mumbo-jumbo. Another solid patch for my powerbook.  
(Version 10.4.3)

ANONYMOUS  this update messed my mouse up:/ logitech mx510  
(Version 10.4.2)

ANONYMOUS  iTunes stopped working!???  
(Version 10.4.2)

ANONYMOUS  It uses a bit more RAM than Panther, but it is far better, faster, stable, powerful. Tiger ROCKS !!!

Imho it is the best system, and the best version of OS X if you have at least a G4 1 GHz and 512 Mo or 1 Go RAM.

The system is good on a G3 (Finder is fast, great compatibility), but Quicktime 7 and Dashboard need power (lots of RAM). Needs a G3 at 600-900 and 512 Mo RAM or better if you want good speed.  
(Version 10.4.1)

ANONYMOUS  Nothing to report (10.3.8 @ pbalu12 1.33ghz) upgrd went smooth.  
(Version 10.3.8)

WAZZAMATTAU  Although many of the problems reported with the OS X 10.2.8 update are due to issues with the update itself, it's important to point out that, as with most OS updates, many are due to issues with the user's own system. Minor disk and/or permissions corruption can prevent an update from updating properly, and sometimes changes from an update can reveal existing issues that were previously dormant.

Although it would be nice if there were no "maintenance" needed when installing an update, experience dictates that such maintenance can and does make the update process go more smoothly, and in fact has allowed users to avoid many such minor problems. Due to the high volume of problem reports with the pulled Mac OS X 10.2.8 update, now seems like a good time to retrace recommended steps for applying system updates:

1) Before running the update, check your startup drive for damage and repair it, if necessary. The easiest way to do this is to boot from the OS X Install CD and run Disk Utility (from the Installer menu). Click the First Aid tab, select your startup volume, and click "Repair Disk." (If you know how, you can instead start your Mac in single-user mode and use fsck, as this runs the same repair routines.) If you have a third-party disk utility such as Alsoft's DiskWarrior or Norton Disk Doctor, you can also run that for good measure.

2) Before running the update, repair permissions on your boot volume. To do this, launch Disk Utility, select your startup drive, click the First Aid tab, and then click "Repair Disk Permissions."

3) Install the update.

4) After running the update, again repair permissions.

5) If you still have problems, try applying the combo updater for the current release

These steps take only a few minutes, but can dramatically reduce the number of minor problems experienced. In addition, it's always a good idea to back up before installing an update. If you have problems, you can easily restore your previous system from the backup.

(from MacFixit.com, edited and with emphasis added)   
(Version 10.2.8)

DAVIDCRICKETT  Update: This update turned out to let my iMac 233 go to sleep all the time, a sleep from which the only way out was rebooting! I set the Energy Saver to sleep in two hours instead of never, and it solved the instant deadly sleep. After a reboot I set it back to no sleep, and (knock on wood) it seems to be alright! Weird! It took me 24 hours of troubleshooting!  
(Version 10.2.8)

ERIC WOLBROM, CISSP  I found the update to be perfect. Update reboot and it worked.

The complainers are talking about oler updates not this one and were posted months ago,  
(Version 10.2.8)

DAVIDCRICKETT  Absolutely flawless update (as usual). The whiners here have probably tweaked their server, that's no reason to blame Mac OS X Server!  
(Version 10.2.8)

ANONYMOUS  E-MAIL APPLE! How else will they know if you don't notify them.  
(Version 10.2.6)