Although they do look at about the level of the 360's graphics, I remember the previous SC games loving to tout pre-rendered footage as in-game, so I'll wait to see a running video or proper in-game shots before really commentating on the graphics.
I agree about the sequels never quite being as good as the first game though. I've played them all, and they're admittedly all very similar, but the original just had somethign special about it that the other two didn't. I think I played it three times through and never got bored during those, whereas the others got one cursory run and then that was it for their single-player.
Damn good multiplayer though. Hope they refine it some more for this version.