I wouldn't really call it a gapcloser or useful seeing how you don't move for the first moment. Even Triss can rocket jump faster than Aatrox can dash.
The problem a lot of Aatrox mains have is;
Q - Using this in a fight means you deal less damage while also damaging yourself, when you could AA instead. So Aatrox mains tend to not use this skill when dueling unless they want to interrupt a skill (near impossible, but doable) or chase someone who flashed a wall.
W- mix replies on this, some say because of this he's not a real Aatrox and his whole kit is built around it. People wanted Aatrox's kit to be more like his lore and not a weaker Tryndamere with built in lifesteal.
E - You take more damage than this skill usually deals to the enemy, and unless you build Pen it's not effective to use this for poke this past mid game.
R - A ton of people want this skill changed as with an already weak kit which is dependent on Attack speed to function, he gets shut down by Frozen Heart and Omen.
Passive - There was complains simular to Sion how lategame this passive was near pointless because the enemy gets time for their CD to come off. Along with the new GW as a core item which doubles to weaken his W and revive health.
Overall every Aatrox main hates how he has weak late game, cant use skills in a duel because he kills himself faster and deals less damage, useless passive which does not scale with anything and is dependant on a stat which can be weaken by 2 items. You can't build HP because it is counter productive and all you can build is damage while having the hp to be 3shot by an adc yet not have any burst despite the fact you are walking glass which kills himself just to stick to you (poorly) so he can AA.
When you get attacked by an Aatrox, it always better to kill him than run. Like swatting a fly. If you want to play Aatrox, play Jax.