Clean install on MacBook Late 2006 (white).
FYI: Tried Leo for just some days back then, early versions sucked, went back to Tiger & never bothered to update again until SL. The migration of my main user from an external USB drive on which I cloned the Tiger install before SL install took some time, but worked fine (most probably - it´s just 2 days now

)
Flaws/glitches and things I just don´t like (or even hate)
1. Battery menubar icon (and pref pane as well) do not allow profiles like before. Esp. if working as a standard user, this is a BIG issue, as you could change the energy profile with the icon, but need to identify as admin now.
On
Flickr somebody complained about the same after update to 10.5.6, in 10.5.7 it was back the post says. Apple - bring it back in SL !!! Prbbly most important reason to downgrade for me :-(
2. The Dock looks ugly when on either side of the screen, IMO. Don´t like the border around the transparent area. Don´t like the area´s color. Heck, I hate the WHOLE Dock color scheme now ... Compared to Tiger of course.
3. Setting options as default for all windows IMO is a setback, does not seem to always work correctly. I think I now have *nearly* what I want after opening a single Finder window, shift-cmd-C to "Computer", change View Options of the "computername" Finder window and hitting "Set to default for all" mostly did it. I don´t like the new style & miss the All/This windows switch in the View Options.
4. Neither Quartz Composer nor Photo Booth allow me to use macam.component supported (non-Apple) web cams anymore. The cams still work in Skype and Comic Life...
5. Just a little thing: Don´t like many of the new icons. Well - need to get used to it or change them :-/
6. "Help Viewer" is always on top and has no icon in Dock. Hope there is a toggle for this.
7. No more "Text to Speech" in the Services menu. Rightclick on selection works (tried only in textedit and help viewer). And older applications have no Services at all anymore (but we knew before).
8. Not sure about the better SL speed - maybe Tiger wasn´t slower than SL, only Leo was? Pretty happy about the lower disk usage, though.
9. Finder: At the beginning, some programs, files, the Utilities folder had no icons, but somehow they appeared later (dunno why...). Also disconnected network drives sometimes left "ghost" drive icons in Finder windows, but don´t anymore (I think).
10.
And the killer issue: networking problems!
A NAS drive running Samba 3.0.6 does not work correctly anymore:
Copying files to NAS with Finder: OK
Copying files to NAS with cp: OK
Copying files from NAS with Finder: Error, "Unknown Error - 8084", truncated file of length 1032192 bytes (=0xFC000) left at destination
Copying files from NAS with cp: Damaged file at destination, exactly 65536 (=0x10000) byte too short,
NO ERROR, return status 0!!!
Another samba server (3.0.33) appears to work OK.
There were also some NFS issues I have look at again, possibly only in Terminals, not when using Finder, but have to recheck to be sure.
Will downgrade back to Tiger again on my MacBook and install SL on an external drive for testing. Unless energy profiles (pmset still has them, though the pref pane doesnt care) are re-enabled, SL is much less useful on notebooks (and I would go so far to say I would not buy any Macbook again, as I planned before SL - pretty sure Win7 will do this better!). The networking problems is (for me) a real killer as I cannot update samba 3.0.6 on that NAS drive anytime soon. Throw in the QC issues, that´s it for me.
Hope they´ll fix this... if not, I will be stuck with 10.4. and no more mobile Apples for me :-(