Heroes 5.5 WarGame Edition - Tactical Edition.

Does the mod affect the graphical aspects?

I personally don't work on the graphical aspects, so for now – it doesn't. However, there are plans to involve people from outside and repaint some textures, at the very least.
For example, the Elves will have emerald, gold, and azure dragons, and the Mages are planned to have marble, onyx, and obsidian gargoyles, stone, steel, and diamond golems. There may also be Ifrits as one of the types of Djinns.