G3CD  Apple had these OS available as a free download on their FTP-server ages ago (before you were born, in the late 90s)  
(Version 1.0)

G3CD  I don't see how 3D and graphics acceleration are better supported. All I see is that flash videos become painfully slow in Safari (though they're somewhat faster in Firefox). I'll go back to v9.  
(Version 10.0d536)

G3CD  After just moving Perian 1.1 to my prefpanes folder without even clicking on "install" in the system preferences, my Powerbook crashed twice with the multi-language screen and video-playback got veeeeery slow with lots of waiting time while some cache filled up.

OS X 10.4.11, QuickTime 7.4.1 here.  
(Version 1.1)

G3CD  Office 2008 looks a bit different - the buttons in Entourage are a bit easier to recognize, but that's just about it. I didn't discover anything really new right now. The new application icons are ugly though.

There are a few things that don't work quite as expected:

- spam filters are more lax in 2008 than in 2004, had to change setting from "low" to "high" to get the same results

- Entourage 2008 imports 2004's rules, but it doesn't recognize the folders right away: if I want to move a mail automatically to "friends In", I have to open the rule, re-select the subfolder "friends In" and THEN it'll work, but not initially.

- if you have lots of error messages in your log, you can't delete them all as Entourage tries to open a confirmation window for each. I had to force-quit Entourage after a night without a network connection.

- it still takes Entourage 2008 40 seconds to open my "SPAM rule" with something like 150 conditions in it. I'd say, Office 2008 didn't get any faster.

On the bright side, I'm now confident I can open and use Office files for a few more years ...  
(Version 12.0)

G3CD  Used CCC 3.0.1 to backup a 10.5.1 installation. Target volume wasn't bootable and when I solved this by reinstalling OS X since I didn't want to wait 5 hrs for CCC to copy all the applications again, I found that most icons and labels were missing.

So, apart from "synchronising" everything for up to 2,5 hrs (even when the target disk is EMPTY!!!), CCC 3.0.1 seemingly failed to copy some permissions (hence not bootable), labels and icons. I couldn't find preferences for making a target disk bootable like in 2.3, maybe that's why. CCC 3.0.1 gives you the feeling it's going to take care of everything but doesn't give very good feedback. And at least in my case, it failed to do its job.

I like that CCC 3.0.1 is more responsive and shows the overall progress better, but I went back to CCC 2.3 for essential backups.  
(Version 3.0.1)

G3CD  Works great with my Sony Ericsson T68i after OS X 10.5 has crippled SMS functionality. Addressbook support works neat, setup could be somewhat easier, maybe though listung of already paired BT devices. I wish I could receive SMS, too, like Addressbook used to do.  
(Version 1.85)