Short answer – Snow Leopard is proving to be the best OS X update in years. For the first time in longer than I can recall an Apple OS upgrade completed in less than an hour, did not break my existing applications and primary workflows, and actually nets positive in all significant areas (performance, usability, elegance).

That being said, not everything is hearts and flowers, but the negatives are third-party incompatibilities and not deal-breakers.

• Line 6′s most awesome Pod Farm AudioUnit plug-in isn’t yet compatible. I’m back to using real mics and amps for now, but as most of my work is mixing/sequencing right now I’ve got some time to spare for this to resolve.
• Xmarks bookmark sync (reasonably indispensible, but I know it’ll get ported quickly).
• When creating a new event in iCal using the Exchange integration, it doesn’t always invite the room I’ve specified unless I drag the event to a new time, and then back to the correct one. Weird!

All things told- still two thumbs up!