Reactions to Apple's Leopard are, well, they're like you expect with a new OS release: good, bad, mixed.
The good comes from Macworld with its review by Jason Snell, which we can sum up with its summation:
Pros: Easy backup tools; major improvements in included applications; addresses numerous shortcomings from previous OS versions; improved security and networking functions.
Cons: Stacks and Dock features seem poorly thought out; illegible menu items with some Desktop backgrounds; some bugs in Spaces window behavior.
OK, and the bad includes Matt Neuberg of TidBITS with his Leopard moan, which covers the new Help assistant (which doesn't), Stacks, the lack of Classic, the menu bars and so on.
Dave Winer's reaction so far could be summed up as "meh".
And Chuck Shotton (via Winer) noted a potential problem:
The Migration Assistant app fails silently in the Installer if your old account's name is the same as your new account's name. So....
And commented:
How many THOUSANDS of people are gonna run into this same issue? How logical is it to make your new username the same as your old one? Very.
And for which the fix is:
If you do a clean install, pick some disposable name for the first user account, then the Migration of your old account will happen OK.
John Gruber meanwhile has extremely sensible advice on how to upgrade. It does entail having something which can make a bootable backup of your existing system, and an external hard drive. But you have, don't you? Read his advice first, I'd say.
Update: as some commenters have noted (thanks!), if you've installed Unsanity's Application Program Enhancer (APE - or "Enhancer" as Apple puts it), you'll get a BSOD - you know, blue screen of death - on reboot after your install. Apple has a support document about it. Solution: remove the "enhancer" and/or do an "Archive and Install".
Another update: Skype has issues - it will only launch once (because the application file changes after its first launch). The problem is the firewall notices it's changed and so block it. Solution: wait for a Skype update, or keep reinstalling it from the .dmg disk image.