You should keep in mind that these are technical support forums. Generally, the only people posting here are those with problems. The thousands/millions without problems don't ever come here.
I've
NEVER had a problem w/any of Apple's updates.
*A few updating tips:*
+1) Firstly its is always a very good idea to repair permissions (using Disk Utility) and to "repair disk" (either by using Disk Utility from the "utilities" menu in the menubar while booted from the iMac or Tiger DVD, or by starting up in "Safe" mode - see
http://docs.info.apple.com/article.html?artnum=107393 ) before installing ANY OS update. This can greatly reduce the possibility of problems occuring.+
+2) When updating remove ALL non Apple USB and Firewire peripherals while undertaking the update.+
+3) Use the "Combo" versions of the appropriate updater, rather than the one provided by Software Update or the "delta" version on the download site. The "Combo" updater will be much larger than the "softwareUpdate" or "Delta" versions, but it replaces many additional files which may have become corrupted or suffer from other problems.
+4), if your computer is having significant operating problems be wary about trying to use an OS update to "fix" them. Things like regular "spinning beachballs" on a computer with adequate RAM, for example, are likely to be caused by directory corruption, or hardware problems, or other such issues. Installing an update "over the top" of these problems can actually make things much worse. Updates usually involve a very large amount of disk activity, with thousands of files being written and deleted. If the directories are troubled aready, then they are likely to be fried completely by the time the install is completed. Better to sort out the problems first, before updating.+
+5) Do not attempt to update if you have limited HD space available. You should ALWAYS aim to have AT LEAST several gigabytes free on your HD. Installing OS updates causes a large amount of free space fragmentation. On a disk with limited available free space this can be disasterous.+
+6) Do not do run other software , surf the net, check your email or design your new house on the computer while the computer's OS is being updated. You can download it in the background if you like, but, it is ALWAYS a good idea to restart before actually installing the update, and to do nothing else with the computer until it has completed the installation and been rebooted again.+
+7) If problems DO emerge after the update, its worth repeating Step one to 3 above. Its also a good idea to add your peripherals one at a time and test them. Sometimes updated drivers may be needed for some devices, or they may simply be incompatible with the new version of the OS. ("Wake from sleep" problems are often associated with this). If you have already updated and are having issues, repeat the process, repairing permissions and the disk, downloading the Combo updater, disconnecting all "non-Apple" peripherals, and running the Combo installer.+
+Older third party "background" software on occasion produces problems too, so if you have virus checkers or other third party items enabled in your System/Preferences /Accounts / LogIn items tab then disabling them can be a good idea while trying to resolve the issue.+
+Usually these things go without a hitch for most people without any problems at all, using the steps outlined above) , but a bit of preparation is a good idea for everyone. It is usually much easier to avoid the problems in the first place rather than to resolve them afterwards.+
_The above authored by Rod Hagen(L4)_