Visually, Aatrox’s rework isn’t much of a change in comparison to the other reworks, like Swain’s or Poppy’s. The only things that have really changed on his design is his sword and his huge wings. That being said, his model and splash art have been updated to show his new gear.
Aatrox is still the goth-y Darkin we know (and love), and he gets the update he deserves in his base splash art. His kit changes are much more dramatic and you can see all of his new stuff here.
All of his skins had splash art that aged pretty nicely. Despite the fact that Justicar Aatrox came out in 2013, the splash art looks pretty good still!
These updates are all on the Public Beta Environment now and Aatrox’s rework should go to live servers in patch 8.13. All of these changes are subject to change before release.