The Health bonuses do not work, at least not in sandbox. Attack works fine.
Army size should be increased drastically over the course of the game, level ups need to be changed to be more interesting, enemy variety is abysmal and needs implementation, Lancers are terrible (5 unit slots for 1 is absurd), addition of magic in battles would be superb (variety of ways this can be implemented), and finally my biggest gripe is the stat bloat.
That last part might sound strange considering this is an incremental game but it's also a battler, thus stats bloating to the point of nigh meaninglessness is actually very bad. Having knights with 10k HP means nothing if they're still dying in a couple hits. Also can't even compare unit stats to the enemy in the regular game.
As the game is, archers are the only significant force multiplier.