I didn't like how they reworked Commander bonuses.
For the uninitiated, every Advance Wars game up until Days of Ruin had Commanding Officers who provided bonuses and penalties to all of your units. By dealing and taking enough damage, COs could use a special power (or two) as a sort of limit break.
In DoR, however, you have to place your commander in one of your units, and only that one would get any real advantage. Powers would only affect nearby units, and power could only be built up with the commanding unit - and the enemy AI prioritizes attacking your CO. Lose the commanding unit, lose your power. Bleh.
The story and gameplay were excellent for the most part, though. I still kinda prefer Dual Strike for the sheer amount of potential strategy.
I can completely see why they revamped the commander bonuses. I can't really vouch for the earlier games but DS was hilariously unbalanced and swingy due to
a) Some commanders simply having abilities that were simply too good. Grit and Colin were the ones I remember. Grit's basically turned artillery into cheap rockets and let you inevitably win through attrition when using a meatshield, while Colin again allows you to win on attrition due to cheaper units and being able to tag out to someone with decent attack when you need it. I seem to remember Hachi's Super CO power having a tendancy to cause you to win on some maps too.
b) Tag powers being ridiculous and often game deciding. It's not so much "strategy" if the first person to get tag power crushes everything the opponent has and leaves them with no way to retaliate.
I mean, sure, it was awesome to OHKO my opponent in one of the last missions of the campaign with an infantry unit that was
20 squares away from my opponent's HQ at the start of the turn, but I don't imagine that things like that are conducive to balance or fairness.