Features : Better Textures. Higher quality. More yellow'ish texture to match the old model and the game's concept art. Dirtier Look. Darker color. Special thanks : T-braze. Jersongaming. Valve. Photoshop.
I don't want to be mean or anything but it looks like you just went over the original skin with some photoshop brush presets and it looks awful. You really need to work on your texturing. Also you haven't applied any texture edits you've made to the specular map so they won't be shown in the model's lighting (although this is more of an extra detail you could've added).
Quite frankly I don't see why this skin needs so many revisions made to it, Jerson's upload looks fine (save the broken smoothing).