No "generic" artillery/ATG's. Right now there is no difference between a 76.2mm FH, a Katyusha rocket, or the mega German railway gun used at Sevastopol.
Better, less vague, realistic TO&E for all units.
Support units (engineers, both combat and construction, aviation support, AFV repair units, etc) similar to WITP.
Use of captured equipment (but realistically done) as happened frequently on Eastern Front.
More different types of specialized units that actually have a useful and appropriate function (IE combat engineers for urban warfare, etc.)
More lower level commanders.
Better modeling of Western Front and North Africa/Italy, better modeling of strategic bombing campaign and if they are going to have bombing in the game include the RAF, too.
Ability to control air missions like in WITP...IE if you want half of your BF-109's to escort your Stukas and the other half to stay back and fly CAP you can adjust percentages of each mission type.
More and smaller air units.
Recon aircraft and ability to order specific aerial recon missions, better ground recon, none of this abstract "combat value" BS, if an enemy division has been in the front lines in the same enemy Korps/Army for a month in the same hex I should know it's there and have some idea of how strong it is (subject to fog of war, etc)