I just picked up a copy of Leopard and am LOVING it so far. Spaces, stacks, cover flow and the new finder — alone — make it worth the upgrade.
Although I have found one minor issue. When mounting a hidden share (active directory smb://servername/share$) it mounts it as you would expect… but then when you go browse back to in finder it will not display the share.
Now when mounting a share it will display the server name in the left area of finder, when clicking on that server it displays all shares that you have access to. I am assuming because the share is hidden it is unable to enumerate it from the server, but it obviosly works because it opened it when I specificly told it where the share is located.
Hopefully they fix this in a update because I am not able to find anything on it on their support site.