The difference from Photoshop CS is very marginal for my purpose so I'm not upgrading.
Vanishing points, smart objects, event-based scripts and variables do seem nifty, but really I'm fine with the current version of PS i'm using. The upgrade for a few extra features might not be worth the extra memory/cpu usage of the new version. For me, Adobe's been notorious with ridiculously upsizing their system requirements for every new version.
some awesome stuff here. it's not a great buy if you're a casual user, but for people who spend 8 hours of their M-F in photoshop, some of these new features are great. multiple layer control, image warp, smart objects - all very big improvements. also, the inclusion of an animation palette begs the question - are they doing away with imageready, finally?
i'm seeing some consolidation going on here, with photoshop taking on some very illustrator-esque characteristics. i wouldnt be surprised if CS3 shipped with photoshop and illustrator fully integrated into each other as one product with the same interactivity with flash that photoshop and imageready have now (one click transfer, same basic interface, etc).