Finished watching the regular edition yesterday.
While the audio wasn't spectacular, it wasn't horrible either.
But the video sucked. Too much compression means loss of fine detail. And the regular edition of Spidey 2 is a good example of loss of fine detail.
So while I've not seen the Superbit version yet, the video has got to be a good deal better on the SB release.
And I'd hope that either the DTS or higher bitrate DD track on the SB release would sound better. Maybe that's the whole reason the regular release sounded only average at best, so that it'd be easier to notice an improvement when watching the SB release...