There will be no spoilers here.
The Decepticons (BGs) took over the city of Chicago. They wiped out the majority of the city and populace in it. It made me smile for a couple of reasons. One, it was poetic justice to see the most liberal and screwed up city get wiped out. Two, it was fake, so I didn't have to feel guilty about actual people getting hurt.
More movies need to blow Chicago up.
It was an enjoyable movie as well. Nothing great, nothing horrible, but good enough to make me enjoy having spent the time to see it.