Just finished the game, playing on hard all the way through!

Well, almost finished the game. Still trying to find my wife after conquering the realm. I suspect Maxos might have kidnapped her in ways of the architect to force the fall of yet another empire into DLC or a Dragon Commander 2 that I'll happily buy.
I loved the game. People say that the RTS part is blobby, but "blob" doesn't do the game justice. I used to play RTS where I created catch all defences, endured blows for an hour before swinging back. Now, that's a blob.
This game completely changed my outlook and after figuring it out, I'd like to think of Dragon Commander's RTS as a 20 minute knife fight with rapiers. Those blobs are ruthless razor cuts. Parry, lunge, stab while the AI is unbalanced.

I have to say though, that Act 3 was a downright nightmare, let alone on hard. I feel I've only won because I the AI is a bit more dim on the empire map, and because of what I fear is a bug.
I noticed how all my cards, funds and research points carried over from Act2 onto Act3. I didn't take advantage, but it did leave me with an enormous warchest and more mercenary cards than I ever needed. After surviving the initial onslaught, I could simply buy my way to victory. It didn't matter how good the AI was in tactical combat, I would simply slap on so many mercenaries that I could auto-resolve ahead of that with my upgraded generals. It didn't matter how I ran my empire or how much larger my enemy was, I could churn out expensive units non-stop on the fat I had collected in Act 2.
That said, I was frugal at times and simply faced the AI in situation where I was evenly matched. I soon dreaded it when I did however. A lot of micromanaging is involved and (at least the hard AI) does cheat in the way that it is far better than you at it. It also ruthlessly exploits what I feel are disbalances that kinda make the combat joyless.
Massed Devastators, have no ground-based counters, which I resent. My armor divisions easily countered them before, but in Act 3 I saw such a build up of them, that they were capable of pulverizing anything before it got close. The only solution to that is abilities like the Warlock's death from above or a zeppelin's mustard gas, but this is where the AI had a definite leg up. On skill use, which is highly micromanagement oriented, the AI constantly cheats by doing this with such efficiency that I can't emulate it. Constant shaman shields pop up, my troops get turned into beetles, mustard gas everywhere. I absolutely hate how the AI is capable of bubbling a tight cluster of 12 units, who then proceed to take on an army of mine that is 4 times larger. I'd give Maxos' beard for a dragon spell that cancels all of the enemy's magical effects in the area. Those bubbled units would last 5 seconds instead of 30.
Micromanaging a response to that is nearly impossible. In short succession I need to: Redirect fire on unbubbled units, dispell beetle on my units, bubble my own units, make sure my units are keeping suicide troopers at bay, make sure my shamans don't stray to the front, operate my dragon, steer my units out of AoE effects and make sure my factories are doing a decent job of churning out reinforcements. At most I can do 4 of these things, resulting in horrific losses only negated by my dragon and the fact that my armies always counter theirs. A lot would be resolved if that same enemy AI would concern itself with micromanaging the abilities of my own units. Maybe not trooper's suicide, but the shaman's dispell or bubble on the most hit unit for example.
Act 2 was fun and fine. But after a few of these horrific act 3 battles, I resolved never to engage the AI again on fair terms. I would always have enough units to crush him on the empire map, which is something the AI happily obliged by steering transports full of units into the waiting hands of my fleet, or throwing only small armies at me. I'm not sure if the act 3 empire map is variable, but blockading his supply routes across the oceans is nice and simple while creeping a huge army towards his scattered forces on way to the capital. Then again, that's easy for me to say with enough money to create fleet upon fleet of ironclad and juggernaughts. :P