In summary:
Like the PS3, 360, PS2 and PC versions, it appears to lack a couple of effects from the GCN and Wii versions -- namely, the blur filter (DOF) and specular highlights (which make certain monsters look "slimy").
This version appears to have the cleanest image quality, however. Dolphin can achieve similar results, but this is the cleanest you can get "officially."
There was some debate here about whether the lighting has been changed. It appears the lighting changes are not in-game, but rather the work of Capcom editing screenshots after they were taken. This would explain inconsistencies in the PC screens. Also, the lighting in the Steam trailer looks fine. In other words, the lighting has probably not been changed.
The biggest boon for the PC version is the 60 frames per second -- it will run twice as smoothly, really *popping* off the screen. The controls will also be much more responsive at 60 fps. It should be the best-looking in motion, and the best-playing.
In terms of content, it has everything -- Separate Ways, the cutscene viewer, the special weapons and costumes, etc.
Not bad for $20. Still one of the greatest games ever!