These are my observations since moving from D2 to DKS.
- overhauled quest rewards
- better game performance overall
- some NPCs received different heads/clothes/equipment (same voices)
- many set items and personal/class items can be purchased from vendors, as early as Broken Valley Village, and/or found in the wild.
- most personal gear, such as is found after reading minds, has been reworked
- gear is more Shiny!
- the DKS:ED campaign's end seamlessly transitions to FoV's beginning (Had it not been for meta knowledge, I wouldn't have known I was moving to a different campaign.)
- anti-dragon zones have been mostly removed from fortresses; the exception being one at Stone's fortress
- contrast improved so dungeons feel darker and outdoor areas feel brighter (still a lot of 'fog' around Broken Valley Village, for some reason)
- quest items, keys, and other special items sparkle so it's very hard to miss them (this might be part of a recent patch to both games - my memory is fuzzy)
Edit: I don't recall seeing any new quests prior to FoV. I was using a walkthrough to make sure I didn't miss anything. Perhaps they added more ways to solve certain quests?
As far as I can tell, many of those seem to be the case with ED+FoV too, so it looks like any differences might be minor. The bits I'm not so certain about is the extra personal stuff, though it does seem that vendors have a wider range of goods for sale unless my memory is playing tricks, and the transition to FoV itself since I haven't got that far yet. The visual effects are the most obvious such as the darker dungeons, and I quite like the sparkly items though I can see some people objecting to the "handholding"!
Well it looks like the upgraded ED probably isn't missing too much (or indeed anything) from DKS, which is good to know.
