The Steam version is compatible with the latest version of the mod DsFix (2.2)
As for the goodies, mini-artbook is 152 pages. The poster is 56cm wide by 86cm high. The DVD "making-of" is actually a series of small marketing clips. You do not learn much. The audio CD contains 23 tracks. It contains all the music of the game except the start menu.
In short worship Steam compatible game with some nice goodies at reasonable prices.