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).