Wide variety of units to use.
Explosions feel and look good. (In other words, it doesn't look like a fire cracker went off when a artillery shell hits a surface.)
Pretty good destruction Physics.
Covers both World War One and Two Warfare, so it caters to both interests. (Refreshing concept I have to say.)
Detailed animations on units.
Limited soundtrack. (It's good but needs more variety.)
Some bugs, typos, etc. (But nothing really new from what I see in other big games like this.)
Occasional wonky AI. (Although that isn't really a new problem in the Strategy genre.)
Tutorial covers only one portion of the game. (The battling portion of the game isn't too hard to understand. But it would be nice to have an explanation on what to do.)
Overall, despite the flaws Aggression has, it is still a fun RTS to play. Theres a huge amount of content in this game, so for ten bucks you can't really go wrong.