Remember, the 360 version of Dark Souls is a port. From Software is only making the PS3 version, while the 360 port is handled by Bandai Namco. The fact that they've never shown the 360 version to the public is...suspicious, to say at least.
In other words, brace yourself for an inferior version.
That would be the second or third game that is inferior on the x360 in any quantifiable way.
(Let me qualify that by saying that I'll still take a PS3 version over x360, if at all possible).
"Problem" is, some games are very big. And with Dark Souls, you have virtually one big world that you can't chop up into 2 or 3 disks. That works with Mass Effect, but Dark Souls isn't that sort of game. So of course Bandai was forced to pack DS onto a single disk for 360, which I presume will mean loss in audio quality and maybe worse textures.
Since Microsoft policy doesn't allow multiple-disk full installs only, 360 gamers are getting the shaft. I wonder who came up with the stupid idea there to ship 360 SKUs without a hard drive in the first place...