Badly written, badly acted--- and even the fight scenes were just not all that cool. How can Michael Bay not get giant robot fights correct? I don't know.
Too much General Motors porn. Too much product placement in general. Several scenes felt like commercials. Also, being sandwiched between your girlfriend and your robot? Pretty kinky.
How did Megatron manage to crash-land (duh--- "gravity") but still figure out where the cube was with any degree of accuracy?
Why don't the Decepticons (or Sector 7) just bid for the stupid glasses on E-Bay? "Buy it now"!
Perhaps in the Michael-Bay-verse it's some other city, but in our world, the nearest city to the Hoover Dam is Las Vegas. It's kinda distinctive.
Why must all of the 20th centuries technologies always be reverse-engineered from aliens? We did OK in the 19th century without aliens, didn't we? How about, just for a change, the aliens give us useless technology like improved horse collars or something?
Why does the All-Spark only turn our technology into eeeeevil robots? Why shouldn't Nokia-cell-phone-bot be friendly? Or Soda-machine-bot?