There were two builds there. The Xbox 360 build was 85% completed and is the most recent version from Sega. By comparision, one of the reps informed me the Live Marketplace demo was essentially an updated E3 build. The X360 version is still set for November something-teen, while the PS3 version is set for Winter 2006 (not a launch title). The PS3 version was present at 75% completition. It was the TGS build, but played identical to the X360 build.
The demo consisted of Kingdom Valley with the ruins and wind grinding we've all seen at this point. Sonic, Shadow , and Silver were all playable. I personally haven't played any previous versions (including the Live demo), but I was particulary pleased with what I played. Knowing well in advance about the change in homing attack, I personally found it worked out rather nice. Although it still needs tweaking, I found it being more natural and graceful for Sonic being at the height of the attack before pulling off another. It seems slower, but more fluid than the infinite homing attack of pwnage of previous games. The control needs some tweaking at max speed, as a slight shift when runnning at full sends Sonic swinging in either direction. Sonic's sliding attack needs work, as I was gliding over the stone like it was ice for 10 seconds without slowdown. Camera worked out much better than I expected, with only occasional problems when playing as Silver.
Shadow's stage worked out additionally wel, but control on Shadow himself needs work. In one sequence I had to smash a stained glass window open. I used Attack to make Shadow go through the whole breakdance kick sequence, but the glass didn't break until the very last clip of the animation, with the glass not moving until then. Also, I'm not sure if this is intended or not, but every Chaos Spear I threw thrusted me in the air even higher. I could do this forever to save myself from falling to death, even with no enemies around. The homing attack on Shadow also seemed to be a bit more refined than on Sonic, requiring less wait time for the next attack to chain. Getting enough crystal energy let Shadow use the Chaos Control/Blast special, turning him red.
Silver's stage was a mixed bag. I enjoyed grabbing all the crates and the bullets and throwing them back at the enemies. The bullets however, still need tweaking, as I grabbed a group of them, and a few more came right aftwerwards and didnt get grabbed.
Lots of franchises have shows that end but continue to pump games out with the same cast used. 4Kids is especially a company known to want to pump out as much as they can in order to get money.