Yup, I've noticed the domes. I like the fact that it indeed looks like it's the home of all bad, too. Maybe I don't remember that much, but hell, I never thought this planet is actually that well-conditioned. On the other hand, this would explain why everything blew up so easily the moment you destroyed the Midian Controller.

Yes, it certainly is that planet. At first, your Seeding Pod was sent on its surface when its Satellite Command Center or something got blown up because of you, then you had to face the enemy's incredible resistance. After you wiped everything nearby that protected the Controller (well, not everything, but definitely the "obstacles"), you descended deep into the enemy's awesomely-constructed tunnels. Yeah, they were awesome, I highly doubt most RTS games actually had indoor combat back then. And then, all you needed to do is to destroy the shield generators and blow up the mechanical mastermind himself (itself?). But it sounds easier than it is, really.

The other planets I liked the most were Talok (well, it's a moon, but nevermind), Eden4 (go reddies!), Gracko (even if the mission on it was so short, it was fun) and Dogbar Max (additional points for the cool cinematic in the end).

And now, something slightly different. We're still talking about silicon.
Now, my favorite units were definitely Technicians, Reapers and Warlords. They sound really cool! Technicians maybe aren't as "badass" as the other machines, but they always sound so incredibly scared and stressed when you select them or when they're attacked. I think that's cool, you can actually feel your machines are trusting and fearing you at the same moment.
Also, I liked the Overseer's demo voice lines. He/it sounded really, really fanatic (but cool). Not to forget the demo's Controller's voice. I think that one suited him/it way more.

For some reason, I've noticed the closer the victory is, the more suicidal tasks the Controller brings upon the player. And I don't really mean the fact that it's getting harder, I mean stuff like "blow up the satellite that controls other satellites, forget about all the units inside it, they will go to Silicon Heaven". But I don't think the Controller doesn't care about his servants, really...

Also, I consider the failure messages to be quite funny.
Just look at this one: "Destroying your machine is not the way to succeed in our struggle against the enemy." It's from the first tutorial level. It begins rather politely, but as you proceed:
"Destroying yourself is not the way to succeed in our struggle against the enemy.". It clearly shows you'll be penalized and probably killed if you keep being dumb. Then:
"Resource is the key to success in our war. If you fail in this, then our mission is doomed.". Our overseer clearly tells us it's serious business. In the fourth tutorial level, the overseer sounds like he's mocking us:
"Failing to destroy 'dummy' targets does not bode well for the machines under your control!", which basically means "Why the hell are you even playing this game if you can't destroy fucking dummies, dumbass!"
The fifth tutorial level is a bit harder, but here, he/it won't mock us at all, just give us a hint, so I won't mention that.

The further you progress and the more you're trusted, the more harsh the failure messages will be. For example, when you fail the Talonthia 8 mission, you get this:
"Talonthia 8 is still in the clutches of the enemy. Our effectiveness in this sector is clearly reduced by your mechanical incompetence." Or, when you fail the Kidnapping mission:
"The mission is a total failure. The controller is considering having you recycled." Oh, so it's on!
Probably the only level without you being criticized for your trying is the Home level:
"The controller thanks you for your efforts, inadequate though they were." But it still sounds like the overseer (or the Controller) does mock you.

And at the last level, it gets REALLY brutal:
"You have failed, and our strike against the enemy has foundered. You should be smelted for your incompetence in our most critical hour." But this one has a slight taste of lamenting and anger, if machines can feel.

I love these messages. You can open the "bin" files in the "pdata" folder with a notepad and read them, if you didn't know it before.
Try that with Dogbar Max. There's a nice ("nice") line of text the overseer made.