What features does this mod provide to me?

You can toggle a "Fullbright" feature within the config (accessible inside the Mod Menu UI) and by pressing the configured keybind (G by default)
There is also a permanent night vision toggle, also found within the config and toggleable using it's own keybind (H by default)

Why not just use "Gamma Utils"?

This mod uses different means of modifying how the gamma is handled, meaning it doesn't "taint" your game's options file.