Splinter Cell: Double Agent is, to my knowledge, the only game released on two generations of hardware where the alternate version for the previous generation is actually better than the one for the current generation. I’m only about halfway through, but, so far, Double Agent for the original XBOX is superior to its big brother in every way, with the graphics being the obvious exception.
The story is improved quite a bit. The JBA seems much more suspicious of Sam Fisher, and in the missions I’ve played, the JBA work as a team, with Sam being one part of a larger plan. The fact that the JBA sent Sam, their newest member who joined the group through a bizarre set of circumstances, alone in the field to complete their most important objectives in the 360 version never made sense.
A single trust meter makes more sense. In the 360 version, there were two different trust meters, one for the JBA and one for Third Echelon, and it took very little effort to keep both meters full. The Xbox version has one trust meter, and it’s a constant balancing act to keep both factions’ trust, because everything goes poopie if the meter steers too far in one direction.