All of the problems with the Halo 3 beta release this week seem to have clouded the interesting stuff - like what it's actually like to play.

Of the comments I have heard (including those as part of IGN, who also have some wonderful videos of the multiplayer levels), one of them is that the quality of the rendering does not look that different from Halo 2.

Now, I don't know which version of Halo 2 they have been playing, but Halo 3 looks much better to my eyes, and this comparison video does a pretty good job of showing the differences.