The small pov on the battle and large amount of unit movement is the biggest problem here...
With no way to gauge how well your troops are fighting, nor really if they are hitting anything, or with which weapon, you get no sense of control over the battle. The game devolves into mashing buttons and spamming troops.
Need a minimap, slower less bouncy troop movements, or maybe just a way to pull back the pov and oversee the whole battlegrounds. Anything to actually see what's going on.
Also, the relative spawn times, troop limits, effects on budget are also hard to evaluate, because of the hard to read HUD vs the fast pace movement of troops. You need a help page that explains costs, time delays and limits before battle, as it's too late to learn on the fly.