I think that CS3 has some really nice advantages over CS2 but am not sure that I (even as a power user) would get the real benefit of them on a daily-use basis. That, and I still run the VERY stable Win2K that CS3 does not support.
As for the cost, you can not buy a better editor for the $$ then Photoshop, but with that said, there are some caveots. The average user and even the advanced, probably do not use PS to even 1/2 of it's operational potential. There is just SO much that t can do, but a LOT that some of us will never use. None the lees, there are some out there that do use the functions that I do not, and that is whey they are in there - for the sake of power and convenience. It is better to have one tool that does more then you could ever need then to have to toggle between TONS of them to get your work done.
... and I prefer not to have to toss my work around if I can do it in one application.