The graphics are just the killing blow. Play DoW 1 + expansions and you'll see the only reason SC is still in peoples minds as a great game is becaue it's been around for so long.
I played it back than, loved it. Even after playing DoW 1 + expansions I was sure to play SC 2, but solely because of the fluff/background. Graphically it will be just a shinny Warcraft 3 in space; gameplay wise it will be the same as before - perhaps with some improvements, but I ain't read anything concerning vast improvements.
But with DoW 2 knocking the door, I don't know if I will bother playing it* (surely won't by it this year, nor in 2009). Squad based, fast-paced action around map control is more my thing today; the mere idea of needing "peasants" (fit ore trucks/whatever here if need be) to gather resources in modern and futuristic games doesn't fit in my mind - it was odd to me even back than when I played SC 1.
Unless the person really likes to focus more on base building and less on full action, and individual soldiers (
)in a more slow paced action, I say: Starcraft II is light-years behind DoW 2.
* All the history of the game will be in wikipedia anyway.