I guess it just depends on your expectations. My computer is hardly top of the line, but the game looks identical to the screenshots, minus HDL and Shader 3.0 (which my graphics card can't handle) and the sharpness afforded by a higher resolution. It looks better than any other current RTS, especially on my machine. No, it doesn't have all the crazy FPS quality graphics that have been floating around (people have taken demo shots that look like the preview screens with comps not much better than mine), but it still has the graphics of a high quality RTS.
As I said earlier, DMUK, the thing holding you back is probably the RAM. Ensemble themselves said that RAM was probably the most important stat in determining the graphics quality. Its also been my experience that demos look much worse than the final game on mid-to-low end comps, especially those with RAM limitations, because they aren't optimized very much (optimization is one of the last things game companies do.
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."-Albert Einstein