I have been playing elemental with 100% auto-resolve. I really enjoy the game, and in my opinion 'auto-resolve' makes the game more challenging, because the normal battles can often become too easy.
With the experience I now have with auto-resolve, I propose the following improvements:
1) When using auto-resolve, it is important to note the order of the units in the army, because this is the other in which they will be attacking the enemy. You don't want your weakest unit to hit first, because of retalliation. My suggestion for improvement is to make it easier to re-arrange the order in the army, and to also make this order load back when you load a game (I notice that the order is changed if you save /load ).
2) Every round, a unit can hit a number of times, depending on the combat speed. The difference with normal battles and auto-resolve, is that in a normal battle, a unit can deal all his hits in a row, whereas in auto-resolve the unit needs to wait for everybody else to make a hit, before hte unit can do a 2nd hit. I propose to bring this in line with normal battles, and thus let the unit deal all its hits in a row, unless the hitpoints go below 20% of maximum (in that case wait for the other units before making another hit).
3) A tactic in normal battles would be to have some units attack the enemy, where others stay behind and use ranged attacks, or wait until they are really needed (because they may for example be on low hitpoints). In practice is is also not possible for all you units to deal a blow in a combat round, because there is simply not enough space to move next to the unit. My suggestion is to let only a maximum number of units deal a blow to a certain unit. I propose to use a maximum of 6 for this. This means that when attacking a single enemy with 11 units, only the first 6 units in my army will do a hit, where the remaining 5 might use a spell or ranged attack if possible, and otherwise they wait for a next round. If any of the first 6 units falls (or goes below 20% hp), the next unit will join the first units that are dealing blows.
4) Possible bugs: Special attacks of heroes are currently not used in auto-resolve. Also area spells have no effect.