The Transformers movies were a huge wasted opportunity - putting aside how bad the scripts / plots were (they were never going to be Shakespeare, but they didn't need to be utterly stupid, full of plot holes and inappropriate jokes) you are still left with the staggering awfulness of the leads.
The performances from Megan Fox and Rosie Huntingdon Whatever her name is were bad enough, but Labeouf was bad in ways rarely seen outside a Star Wars prequel. He's been rotten in everything else I've seen him in too, with the strange exception of 'Holes'. $18 million ? I wouldn't pay him $18 !