Scenes drag on endlessly and senselessly (look how bad that marred Jackson's King Kong). You can make no sense, tactically, of what is supposed to be going on in the last action sequence, which must last 40+ minutes, and which is crosscut with a useless fight between another completely superfluous group and the little bug Decepticon. Contrast how effective is the first fight with the scorpion-like Decepticon, which only involves one robot and must last 10 minutes.
The GMC product placement was a little over the top, the way Dodge used to be on Walker, Texas Ranger.
Powers come and go as necessary. Prime has a sword that can kill with one blow at one point. And the reason he only uses it once? And the cube can suddenly shoot a death ray of some kind, when it needs to?
I checked - the two lead kids are played by 21 year olds, which isn't that far beyond the 16 year olds that they're supposed to be, but boy, do they look old. I don't mean old like me, or old in a bad way, but the girl looks like a very voluptuous woman in her late 20s, not "training bra girl" as the dialogue at one point labels her. I never understand where the teen actors are for movies like this.