I have CS3 (Mac version) upgraded from Studio 8 and CS1.
Dreamweaver is supposed to have some new features -- I've seen references to AJAX stuff, for example -- but I haven't explored any of the new DW features. Dreamweaver doesn't crash 10 times a day any more, so that's a nice improvement. Otherwise, new DW seems much the same as the old DW. I hardly know I'm using a new version, except for the not-crashing.
Photoshop has some very nice new features. Non-destructive filters! A new select tool that is fantabulous, and a "refine selection" feature that I never want to live without. There's something called a "Smart Object" -- sort of a hybrid between a raster image and a vector image, I think -- and I'm sure once I get smart enough for Smart Objects, I'll love them.
Adobe replaced the old File Browser with something called Bridge, which seems to be File Browser made slightly confusing. Or maybe it's just me. I liked the old File Browser just fine.
PS lost its ImageReady component. Supposedly, the IR features were simply included in PhotoShop proper, but there's no longer a palette that shows your slices by name. I liked that palette, and I wish they hadn't ditched it.
There's a "device preview" tool that supposedly allows you to see what your design will look like on cell phones and such. I haven't used it, but it's there.
The menu and palette changes are just sufficient to feel a little uncomfortable at first. I'm still figuring out where or how to do some things that were 2nd nature in Photoshop CS1. (Never had CS2, so I'm two versions behind.) But mostly it's good ol' Photoshop with some nice new features. I'm quite sure I haven't yet discovered some of its best new features -- Photoshop's like that.
I haven't even launched Flash or Fireworks yet. I understand I can now seamlessly launch PS files in FW and vice versa, with layers, styles, etc., intact. I don't need to do that very often, but when I do I'll be glad they play better together now. Oh, and you can copy a file in PS and paste it directly into a DW page, and it gets jpg'd and saved to the site. Very handy on occasion, but not something I do everyday.
Contribute seems moderately faster (or should I say less slow) than the last version. Any improvement there is badly needed.
For me, it was worth the upgrade price. I badly wanted the new Photoshop, both for the new CS3 features and for the CS2 features -- being able to apply text styling to multiple text layers at once, for example. Getting a Dreamweaver that doesn't constantly crash was a nice bonus. Also, I don't like to get too many versions behind on my software. Some years ago when I went from Illustrator 3.2 to 7 in one step, it was like taking a nap and waking up on Mars. So now I try to stay more current with upgrades, and the upgrade price was too sweet to pass up.