I could only find this and take in account that the halo reach footage is blurry and in a prealpha stage.

*spoiler*

What are we comparing? Graphics? Halo Reach wins.

Gameplay? There's still no solid detail as to story, full gameplay, etc so can't compare there.

They're comparing finalized Halo 3 graphics to blurry rumored early leaks of an unfinished Halo. Hmmm. Doesn't seem like the time or place to compare graphics.

Yeah this is a bit early. We dont even know the screenshots shown of Reach might be 12 months old!? Lets wait a bit longer till we have gameplay to show.

Even though the pics are blurry, you can still see that it looks better than Halo 3.

As for how much better, we'll have to wait for in-game video footage. (I'm not gonna trust any screenshots Bungie put out.)