Snow Leopard has been running on two of the three machines at the Apple Harvest for a week now, and all is well. Almost.
Certainly there is a general feeling of robustness which is reassuring for critical software such as an operating system. Most of the issues that have surfaced to date are with third party software rather than direct problems brought about through the upgrade.
I documented the issue with Mail and Keychains in my last blog. I'm aware that a number of other people have had similar problems, in particular with MobileMe accounts. My solution of deleting the default keychain and creating a new one appears to have done the trick, but the problem appears to be more insidious on some installations.
I'm more worried about the incompatibility between versions of Mail and its internal databases across Leopard and Snow Leopard, particularly as a mobile user. It used to be a simple matter of copying the \username\Library\Mail folders between machines before and after journeys, but this option will no longer work across machines with different OS. I keep my primary mail store on my iMac at home and copy the mail folders onto my MBP or Hackintosh before going on a trip. This will no longer work with the Hackintosh (until I'm brave enough to try and upgrade it). This will affect anyone who cannot update their mobile machine with Snow Leopard. There are process work arounds to reduce the impact but it is enough to make me consider going back to using Entourage whilst away from home.
My other real gripe is with my printing ability since the upgrade. I use an HP DeskJet 970CXI printer as a workhorse. I have occasion to have to print quite large documents and the 970 has a full duplex facility for double sided printing. HP do not provide drivers for Leopard or Snow Leopard, and users have to rely on the Gutenprint drivers which have proved excellent. Sadly under Snow Leopard, the double sided printing facility is no longer operational, and is likely to remain that way unless the Gutenprint drivers are modified.
This seems to be a very irresponsible attitude from HP, as their response to concerns from users is "buy a new printer". This applies to any printer over 5 years old. So in my case I either have to purchase a new unnecessary printer or double my paper output. Neither option is environmentally friendly, and neither option is likely to appeal to my bank manager.
Of course I could print out everything through the Hackintosh, but if I upgrade that to Snow Leopard I'll fix my mail issue, but lose my printer fix. Nothing is ever simple is it! I wonder if Windows 7 users will have these problems. Well probably not, they'll have a whole different bunch...
The vast majority of my applications seem to function pretty much as normal under 10.6. Notable exceptions are Bento V1 which won't work at all and the majority of system utilities such as Cocktail, Onyx, TechTools Pro. A lot of suppliers beat the gun and released 10.6 compatible versions of their apps prior to the formal Apple release. Most others have messages on their web sites explaining that upgrades are in preparation and will shortly be available.
For a comprehensive and dynamic list of compatible applications check out the Snow Leopard compatibility wiki.