I just bought the steam version release, and looking through it's directory and subfolders, it looks to be rather easy to mod the game.
Pretty much all the texture files are in a .dds format, which can be easily viewed and edited, as well as spreadsheets used for what texture is being loaded for certain char, enemies, etc. You can even turn on debug mode through FIELD.INI and SYSTEM.INI easily.
There are more than just those things which look to be easily edited as well. The only thing that may be difficult are the 3D models. Granted it already received some improved visuals, but I believe more can be done.