Armageddon is nothing like Guerrilla. I imagine the conversation at THQ went something like this:
"Hey, so, everyone really liked the sandbox gameplay and environmental destruction in Guerrilla, right? So maybe we'll just do more of that, build on it a bit..."
"Actually, I have a better idea. How about instead of that, we scale back the destruction and turn the game into a linear corridor shooter with an insipid storyline, unlikeable characters and bad shooting gameplay that feels like a poor man's Gears of War on a good day? And for shits and giggles, let's introduce a revolutionary game mechanic, only to completely ignore any gameplay effect it could otherwise have to differentiate the game from other shooters!"
"Gentlemen, you've done it again."
In short, it fucking sucks. Don't buy it.