I haven't found it to be significantly better than CS2, at least not in a few hours of playing with it. I have found a few bugs with the marquis tool, it doesn't crash or anything, but there are some display issues. Layout is definitely cleaner. Seems to use way more system resources than CS2. Functionality is about the same as CS2 so far, but it's too early to make any final conclusion.
I think it should be the other way around. Dreamweaver integration with photoshop. Photoshop, at least for the last few years, have been used mainly to slice and export to web formats and it's almost a genre in itself. I may be overlooking something though. What integration are you looking for in photoshop to dreamweaver?