My first impression/criticism list :
1. All Doctrine-type effects should also have a downside. Even a minor downside would help newer players get into the game and not get immediately crushed by more experienced players who have multiple doctrine cards. Matchmaking would also be good, but I assume that will be added when the game is officially released.
2. Practice bot is incredibly weak. Make it cheat resources if necessary, because right now it feels like the bot plays with a resource handicap. Perhaps a difficulty setting to toggle cheating on/off?
3. Speaking of which, there's no tutorial. Okay yeah I get it it's a closed beta. Written guide would be nice though.
4. More numbers! Increases fire rate and move speed? By how much? How much damage do my grenades do? Exactly how much health does an MBT have? I think exact numbers should be shown. It would really help me put together a loadout.
5. Assault units feel exactly the same as rifles with a higher cooldown. An hp buff could help make them competitive. Only use for assaults seems to be using the american deploy assault support card in order to provide a defensive buffer without affecting your cooldowns. This allows you to get a fast mbt out. And that seems kinda strange because their best use is.... Defense?
6. A written explanation on how cooldowns work would be nice. Seems like making rifles delays my MBT by 30 seconds.
7. Target priority could use some looking at. My opponent had two full squads of rifles at my door and we were both running out of units. I played one sniper squad after his rifles started shooting my base and the one sniper squad just cut them down. The rifles never shot the snipers, only my base.